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Brian Shadwick PRELIMINARY PHYSICS

© Science Press 2007 First published 2007 Reprinted 2007, 2008, 2011 Science Press Private Bag 7023 Marrickville NSW 1475 Australia Tel: (02) 9516 1122 Fax: (02) 9550 1915 sales@sciencepress.com.au www.sciencepress.com.auAll rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of Science Press. ABN 98 000 073 861

Contents Introduction v Verbs to Watch vi Dot Points Moving About vii The World Communicates ix Electrical Energy in the Home xi The Cosmic Engine xiii Questions Moving About 1 The World Communicates 45 Electrical Energy in the Home 77 The Cosmic Engine 113 Answers Moving About 147 The World Communicates 157 Electrical Energy in the Home 167 The Cosmic Engine 179 Appendix Data Sheet 187 Formula Sheet 188 Periodic Table 189 Dot Point Preliminary Physics iii Contents Science Press

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Contents iv Dot Point Preliminary Physics Science Press

Introduction What the book includes ,QWKLVERRN\RXZLOO¿QGW\SLFDOH[DPLQDWLRQTXHVWLRQVDQGDQVZHUVIRUHDFKGRWSRLQWLQWKH%RDUGRI6WXGLHV syllabus for each topic in the Year 11 Physics course: ‡ 0RYLQJ$ERXW ‡ (OHFWULFLW\LQWKH+RPH ‡ 7KH:RUOG&RPPXQLFDWHV ‡ 7KH&RVPLF(QJLQH Also included are typical experimental results for students to analyse if the third column of the syllabus indicates WKDWVWXGHQWVVKRXOGFDUU\RXWµ¿UVWKDQGLQYHVWLJDWLRQV¶ Format of the book The book has been formatted in the following way: 1. Main topic statement (column 1 of syllabus) 1.1 etc Syllabus requirement from columns 2 and 3. 1RWHWKDWWKHQXPEHULQJRIWKHVHUHTXLUHPHQWVLVWKHDXWKRU¶VFKRLFHDQGKDVEHHQXVHGWRPDNHUHIHUHQFLQJ TXHVWLRQVDQGDQVZHUVFOHDUHU7KHLQGLYLGXDOUHTXLUHPHQWVDUHQRWQXPEHUHGLQWKHV\OODEXVWKH\DUHVLPSO\ EXOOHWHG±KHQFHRXUXVHRIµGRWSRLQWV¶ZKHQZHUHIHUWRWKHP 1.1.1 )LUVWW\SLFDOTXHVWLRQZKLFKFRXOGEHDVNHGLQDQH[DPLQDWLRQIRUWKLVV\OODEXV  UHTXLUHPHQW 1.1.2 6HFRQGW\SLFDOTXHVWLRQZKLFKFRXOGEHDVNHGLQDQH[DPLQDWLRQIRUWKLVV\OODEXV  UHTXLUHPHQWHWF 7KHQXPEHURIOLQHVSURYLGHGIRUHDFKDQVZHUJLYHVDQLQGLFDWLRQRIKRZPDQ\PDUNVWKHTXHVWLRQPLJKWEH worth in an examination. As a rough rule, every two lines of answer might be worth one mark. Note that in any DQVZHUVWKUHHOLQHVKDYHEHHQSURYLGHGDVWKHDPRXQWRIZULWLQJUHTXLUHGH[FHHGVWZROLQHVEXWWKHSK\VLFV involved is worth only one mark. How to use the book &RPSOHWLQJDOOTXHVWLRQVZLOOSURYLGH\RXZLWKDVXPPDU\RIDOOWKHZRUN\RXQHHGWRNQRZIURPWKHV\OODEXV You may have done work in addition to this with your teacher as extension work. Obviously this is not covered, but you may need to know this additional work for your school exams. :KHQZRUNLQJWKURXJKWKHTXHVWLRQVZULWHWKHDQVZHUV\RXKDYHWRORRNXSLQDGLIIHUHQWFRORXUWRWKRVH\RX NQRZZLWKRXWKDYLQJWRUHVHDUFKWKHZRUN7KLVZLOOSURYLGH\RXZLWKDTXLFNUHIHUHQFHWRZRUN\RXVKRXOG spend more time revising later, and allow you to spend your study time more productively. Dot Point Preliminary Physics v Introduction Science Press

account/account for State reasons for, report on, give an account of, narrate a series of events or transactions. analyse Identify components and the relationships among them, draw out and relate implications. apply Use, utilise, employ in a particular situation. appreciate Make a judgement about the value of something. assess 0DNHDMXGJHPHQWRIYDOXHTXDOLW\RXWFRPHV results or size. calculate 'HWHUPLQHIURPJLYHQIDFWV¿JXUHVRULQIRUPDWLRQ clarify Make clear or plain. classify Arrange into classes, groups or categories. compare Show how things are similar and different. construct Make, build, put together items or arguments. contrast Show how things are different or opposite. critically (analyse/evaluate) Add a degree or level of accuracy, depth, knowledge DQGXQGHUVWDQGLQJORJLFTXHVWLRQLQJUHÀHFWLRQDQG TXDOLW\WRDQDQDO\VLVRUHYDOXDWLRQ deduce Draw conclusions. GH¿QH 6WDWHWKHPHDQLQJRIDQGLGHQWLI\HVVHQWLDOTXDOLWLHV demonstrate Show by example. describe Provide characteristics and features. discuss Identify issues and provide points for and against.distinguish Recognise or note/indicate as being distinct or different from, note difference between things. evaluate Make a judgement based on criteria. examine ,QTXLUHLQWR explain Relate cause and effect, make the relationship between things evident, provide why and/or how. extract Choose relevant and/or appropriate details. extrapolate Infer from what is known. identify Recognise and name. interpret Draw meaning from. investigate 3ODQLQTXLUHLQWRDQGGUDZFRQFOXVLRQVDERXW justify Support an argument or conclusion. outline Sketch in general terms; indicate the main features. predict Suggest what may happen based on available data. propose Put forward (a point of view, idea, argument, suggestion etc) for consideration or action. recall Present remembered ideas, facts or experiences. recommend Provide reasons in favour. recount Retell a series of events. summarise Express concisely the relevant details. synthesise Put together various elements to make a whole. Verbs to Watch Verbs to Watch vi Dot Point Preliminary Physics Science Press

Dot Point Page 1. Speed changes 2 1.1 Identify that a typical journey involves speed changes. 2 1.2 Distinguish between average and instantaneous speed. 2 1.3 Distinguish between scalar and  YHFWRUTXDQWLWLHV   'H¿QHDYHUDJHYHORFLW\DV v av 
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ût 4 1.5 Compare instantaneous and average speed and velocity. 4 1.6 Solve problems and analyse information using: v av 
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ût 5  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR measure average speed of an object. 6 1.8 Graph displacement vs. time data for objects with uniform linear velocity. 8 1.9 Graph displacement vs. time data  IRUREMHFWVZLWKQRQXQLIRUPYHORFLW\  1.10 Present graphically velocity vs. time data for objects with uniform linear velocity. 11 1.11 Present graphically velocity vs. time  GDWDIRUREMHFWVZLWKQRQXQLIRUP linear velocity. 12 2. Forces, acceleration and deceleration 13 2.1 Describe the motion of one body relative to another. 13 2.2 Identify the usefulness of using vector diagrams. 13 2.3 Explain the need for a net external force to act to change velocity. 14 2.4 Describe the actions that must be taken for a vehicle to change direction, speed up and slow down. 14 2.5 Describe effects of external forces on bodies including friction and air resistance. 15 2.6 Analyse the effects of external forces on vehicles. 15Dot Point Page  'H¿QHDYHUDJHDFFHOHUDWLRQDV a av 
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ût = (v – u)/t 15 2.8 Gather information about different situations where acceleration is positive and negative. 16  'H¿QHWKHWHUPVPDVVDQGZHLJKW with reference to effects of gravity. 16 2.10 Outline forces involved in causing a change in the velocity of a vehicle. 17  ,QWHUSUHW1HZWRQ¶V6HFRQG/DZRI  0RWLRQDQGUHODWHLWWRF = ma 18 2.12 Solve problems and analyse  LQIRUPDWLRQXVLQJF = ma 19 2.13 Identify the net force in a wide variety of transport situations and  H[SODLQLWVFRQVHTXHQFHVLQWHUPVRI  1HZWRQ¶V6HFRQGODZ  2.14 Solve problems and analyse information involving: F = mv 2/r for vehicles travelling around curves. 24  3HUIRUP¿UVWKDQGLQYHVWLJDWLRQVWR show the relationship between force, mass and acceleration. 26 2.16 Solve problems using vector  GLDJUDPVWR¿QGUHVXOWDQWYHORFLW\ acceleration and force. 28  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQ to demonstrate vector addition and subtraction. 29 3. Motion and energy changes 30 3.1 Identify that a moving object has kinetic energy and that work done on it can increase that energy. 30 3.2 Solve problems involving the kinetic energy of vehicles and the work done using: E k = ½mv 2 and W = Fs 30 3.3 Describe the energy transformations that occur in collisions. 31 Moving About Dot Point Preliminary Physics vii Moving About Science Press

Dot Point Page 3.4 Analyse information to trace the energy transfers and transformations in collisions leading to irreversible distortions. 32  'H¿QHWKHODZRIFRQVHUYDWLRQRIHQHUJ\  4. Momentum 33  'H¿QHPRPHQWXPDVp = mv 33  'H¿QHLPSXOVHDVI = Ft 33 4.3 Explain conservation of momentum  LQWHUPVRI1HZWRQ¶V7KLUG/DZ  4.4 Solve problems and analyse data using: p = mv and I = Ft 33 4.5 Perform investigations to analyse data for the change in momentum in collisions. 36 4.6 Solve problems to apply the law of conservation of momentum to describe the collision between a moving and a stationary vehicle. 37 4.7 Solve problems to apply the law of conservation of momentum to describe the collision of a moving vehicle with an immovable object. 37 4.8 Solve problems to apply the law of conservation of momentum to the collision between objects moving in opposite directions. 38Dot Point Page 4.9 Solve problems to apply the law of conservation of momentum to the collision between objects moving in the same direction. 38 5. Safety devices 40  'H¿QHWKHLQHUWLDRIDYHKLFOHDVLWV tendency to remain in uniform motion or at rest. 40  $QDO\VH¿UVWRUVHFRQGKDQGGDWD about the potential danger presented by loose objects in a vehicle. 40  'LVFXVVUHDVRQVZK\1HZWRQ¶V  )LUVW/DZRI0RWLRQLVQRWDSSDUHQW in many real world situations. 41 5.4 Assess reasons for low speed zones  LQEXLOWXSDUHDVDQGWKHDGGLWLRQRI airbags and crumple zones to vehicles with respect to impulse and momentum. 41 5.5 Evaluate the effectiveness of some safety features of motor vehicles. 42  $VVHVVEHQH¿WVRIWHFKQRORJLHVIRU avoiding or reducing the effect of a collision. 43 Answers to Moving About 147 Moving About viii Dot Point Preliminary Physics Science Press

Dot Point Page 1. The wave model and information transfer 46 1.1 Describe the energy transformations in one of: mobile telephone, fax or modem, radio, TV (see 3.9). 46 1.2 Describe waves as a transfer of energy that may occur in 1, 2, or 3 dimensions. 46 1.3 Identify that mechanical waves need a medium while electromagnetic  ZDYHVGRQ¶W   'H¿QHDQGDSSO\WKHWHUPVPHGLXP displacement, amplitude, period, compression, rarefaction, crest, trough, transverse, longitudinal,  ZDYHVIUHTXHQF\ZDYHOHQJWKDQG velocity to the wave model. 47 1.5 Describe the relationship between particle motion and direction of energy transfer in waves. 48 1.6 Draw diagrams for transverse and longitudinal waves, directions of particle movement and propagation. 48 1.7 Quantify the relationship between  YHORFLW\IUHTXHQF\DQGZDYHOHQJWK Y I 49 1.8 Perform an experiment to gather  LQIRUPDWLRQDERXWWKHIUHTXHQF\ and amplitude of waves. 50 1.9 Solve problems and analyse data by applying: Y I to a range of situations. 50 1.10 Present and analyse information  IURPGLVSODFHPHQWWLPHJUDSKVIRU transverse wave motion. 51 1.11 Perform an experiment to identify the relationship between the  IUHTXHQF\DQGZDYHOHQJWKRID sound wave at constant velocity. 53 1.12 Perform an experiment to observe the transfer of waves in slinky springs, water and ropes. 53Dot Point Page 2. Sound waves 54 2.1 Identify that sound waves are vibrations of particles in a medium. 54 2.2 Relate compressions and rarefactions of sound waves to crests and troughs of transverse waves. 54  ([SODLQTXDOLWDWLYHO\WKDWSLWFKLV  UHODWHGWRIUHTXHQF\DQGYROXPHWR amplitude of sound waves. 54  ([SODLQDQHFKRDVDUHÀHFWLRQRID sound wave. 54 2.5 Describe the principle of superposition and compare the resulting waves to the original waves in sound. 55 2.6 Present graphs, solve problems and analyse data for superposition of waves. 55  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR observe the superposition of two waves using a CRO or computer. 56  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR analyse sound waves. 57 3. Using the electromagnetic spectrum 58 3.1 Describe emr in terms of their speed in space and their lack of need of a medium for propagation. 58 3.2 Identify electromagnetic wavebands  ¿OWHUHGRXWE\WKHDWPRVSKHUH  HVSHFLDOO\89;UD\VDQGUD\V  3.3 Identify methods for the detection of various wave bands in the em spectrum. 59 3.4 Explain the relationship between the intensity of emr and the distance from a source as an example of the  LQYHUVHVTXDUHODZ   3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR  PRGHOWKHLQYHUVHVTXDUHODZ   2XWOLQHKRZDPSOLWXGHRUIUHTXHQF\ modulation of visible light, microwaves and/or radio waves is used to transmit information. 61 The World Communicates Dot Point Preliminary Physics ix The World Communicates Science Press

Dot Point Page 3.7 Analyse data to identify the em spectrum range used in modern communications. 61 3.8 Discuss problems produced by the limited range of the em spectrum available for communications. 62 1.1 Describe the energy transformations  UHTXLUHGLQRQHRIPRELOHWHOHSKRQH fax or modem, radio, TV. 62 3.9 Analyse data to identify the waves involved in the transfer of energy in one of: mobile telephones, TV or radar. 63 4. 5HÀHFWLRQDQGUHIUDFWLRQRI electromagnetic waves 64 4.1 Describe and apply the law of  UHÀHFWLRQDQGH[SODLQWKHHIIHFWRI  UHÀHFWLRQIURPDSODQHVXUIDFHRQZDYHV  4.2 Perform an experiment to observe the path of light rays and draw diagrams to show direction of travel of light rays and wavefronts. 64 4.3 Present information using ray diagrams to show the path of waves  UHÀHFWHGIURPYDULRXVVXUIDFHV   'HVFULEHRQHDSSOLFDWLRQRIUHÀHFWLRQ for various surfaces. 66 4.5 Describe ways in which applications of light, radio and microwaves have helped information transfer. 67 4.6 Explain that refraction is related to the velocity of a wave in different media and outline how this may result in the bending of a wavefront. 67Dot Point Page  'H¿QHUHIUDFWLYHLQGH[LQWHUPVRI the changes in velocity of a wave in passing from one medium to another. 68  'H¿QH6QHOO¶V/DZ  4.9 Solve problems and analyse  LQIRUPDWLRQXVLQJ6QHOO¶V/DZ  4.10 Perform an investigation to graph the angle of incidence and refraction for light encountering a medium change showing the relationship between these angles. 71  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR calculate the refractive index of glass or perspex. 72 4.12 Identify the conditions necessary for  WRWDOLQWHUQDOUHÀHFWLRQZLWKUHIHUHQFH to the critical angle. 73  2XWOLQHKRZWRWDOLQWHUQDOUHÀHFWLRQ  LVXVHGLQRSWLFDO¿EUHV  5. Technology and electromagnetic waves 75 5.1 Identify types of communication data that are stored or transmitted in digital form. 75 5.2 Discuss some of the physical principles used in one application of physics related to waves in one of the following: GPS, CD technology, DVD technology, the Internet. 76 Answers to The World Communicates 157 The World Communicates x Dot Point Preliminary Physics Science Press

Dot Point Page 1. History of electricity 78 1.1 Discuss how the main sources of domestic energy have changed over time. 78 1.2 Assess some of the impacts of changes in, and increased access to, sources of energy. 78 1.3 Discuss some of the ways on which electricity can be provided in remote locations. 79 1.4 Analyse differing views of Volta and Galvani on animal and chemical electricity. 79 1.5 Discuss whether their (Volta and Galvani) different views contributed to increased understanding of electricity. 81 2. Electricity and electric circuits 82 2.1 Describe the behaviour of electrostatic charges. 82 2.2 Describe the behaviour of  HOHFWURVWDWLF¿HOGV  2.3 Present diagrams to describe electric  ¿HOGVWUHQJWKDQGGLUHFWLRQEHWZHHQ parallel plates. 83 2.4 Present diagrams to describe electric  ¿HOGVWUHQJWKDQGGLUHFWLRQDERXWDQG between positive and negative point charges. 84  'H¿QHWKHXQLWRIHOHFWULFFKDUJHDV the coulomb. 84  'H¿QHHOHFWULF¿HOGDVD¿HOGRIIRUFH  ZLWKVWUHQJWKHTXDOWRWKHIRUFHSHU unit charge at that point, i.e. E = F/Q 85 2.7 Solve problems and analyse information using: E = F/Q 85  'H¿QHHOHFWULFFXUUHQWDVWKHUDWHDW  ZKLFKFKDUJHÀRZVXQGHUWKHLQÀXHQFH  RIDQHOHFWULF¿HOG  2.9 Identify that current can be either direct or alternating. 87 2.10 Describe electric potential difference (voltage) between points as the change in potential energy per unit charge moving from one point to the other. 87Dot Point Page 2.11 Discuss how potential difference changes at points around a circuit. 88 2.12 Perform an experiment to show how potential difference varies between points in a circuit (also 3.3). 89 2.13 Perform an experiment to show the relationship between voltage across, and current in, a circuit (also 3.3). 90 2.14 Solve problems and analyse information using: R = V/I 91 2.15 Identify differences between conductors and insulators. 92  'H¿QHUHVLVWDQFHDVWKHUDWLRRIYROWDJH to current for a particular conductor. 92  'HVFULEHTXDOLWDWLYHO\KRZYDULRXV factors affect the movement of electricity through a conductor. 92 2.18 Identify materials used as conductors to provide household electricity. 93 3. Series and parallel circuits 95 3.1 Identify differences between series and parallel circuits. 95 3.2 Compare parallel and series circuits in terms of voltage across components and current through them. 96 3.3 Perform experiments to compare current and voltage in series circuits (see 2.12 and 2.13). 97  3HUIRUP¿UVWKDQGLQYHVWLJDWLRQVWR compare measurements of current and voltage in parallel circuits. 97 3.5 Identify uses of ammeters and voltmeters. 98 3.6 Explain why ammeters and voltmeters are connected differently in a circuit. 98 3.7 Explain why there are different circuits for lighting, heating and other appliances in a house. 99 3.8 Construct a model to show household circuits. 100 Electrical Energy in the Home Dot Point Preliminary Physics xi Electrical Energy in the Home Science Press

Dot Point Page 4. Electrical power 101 4.1 Explain that power is the rate at which energy is transformed from one form to another. 101 4.2 Identify the relationship between power, potential difference and current. 101  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR demonstrate the relationship between current, voltage and power. 101 4.4 Explain why the kWh is used to measure electrical energy consumption rather than the joule. 103 4.5 Identify that the total amount of energy used depends on the length of time  FXUUHQWLVÀRZLQJDQGFDQEH calculated using: Energy = VIt 104 4.6 Solve problems using: P = VI and Energy = VIt 104 5. 0DJQHWLF¿HOGV 106 5.1 Describe the behaviour of the magnetic poles of bar magnets when they are brought close together. 106  'H¿QHWKHGLUHFWLRQRIWKHPDJQHWLF  ¿HOGDWDSRLQWDVWKHGLUHFWLRQRI force on a small north magnetic pole when placed at that point. 106 5.3 Use and to show the direction of current and and to show the  GLUHFWLRQRIDPDJQHWLF¿HOG Dot Point Page  'HVFULEHWKHPDJQHWLF¿HOGDURXQG pairs of magnetic poles. 106 5.5 Describe the production of a magnetic  ¿HOGE\DQHOHFWULFFXUUHQWFDUU\LQJ conductor and how the right hand  JULSUXOHFDQ¿QGWKHGLUHFWLRQRI  FXUUHQWDQG¿HOGOLQHV   3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR build an electromagnet. 107 5.7 Compare the nature and generation  RIPDJQHWLF¿HOGVE\VROHQRLGVDQG a bar magnet. 108 5.8 Perform an experiment to observe  PDJQHWLF¿HOGVDURXQGEDUPDJQHWV straight conductors and solenoids. 108 5.9 Explain one application of magnetic  ¿HOGVLQKRXVHKROGV  6. Safety devices 110 6.1 Discuss the dangers of electric shock from both 240 volt AC mains supply and various DC voltages, from appliances, on the muscles of the human body. 110 6.2 Describe the functions of circuit breakers, fuses, earthing, double insulation and other safety devices in the home. 110 Answers to Electrical Energy in the Home 167 Electrical Energy in the Home xii Dot Point Preliminary Physics Science Press

Dot Point Page 1. Models of the Universe 114 1.1 Outline historical models of the Universe from the time of Aristotle to that of Newton. 114 1.2 Assess one model of the Universe developed from the time of Aristotle to the time of Newton to identify limitations placed on the development of each by available technology. 115 2. Origins of the Universe 118 2.1 Describe probable origins of the Universe. 118 2.2 Outline the discovery of the expansion of the Universe by Hubble, following its earlier prediction by Friedmann. 122 2.3 Describe the transformation of radiation into matter following the Big Bang. 123 2.4 Identify that Einstein described the  HTXLYDOHQFHRIPDVVDQGHQHUJ\  2.5 Outline how the accretion of galaxies and stars occurred through expansion and cooling of the Universe,  VXEVHTXHQWORVVRISDUWLFOHNLQHWLF energy, gravitational attraction of particles, and lumpiness of gas clouds that allows gravitational collapse. 124 3. Stars and their life cycles 127  'H¿QHWKHUHODWLRQVKLSEHWZHHQWKH temperature of a body and the dominant wavelength of the radiation emitted from that body. 127 3.2 Identify that the surface temperature of a star is related to its colour. 127 3.3 Relate the brightness of an object to its luminosity and distance. 128 3.4 Solve problems to apply the inverse  VTXDUHODZRILQWHQVLW\RIOLJKWWRUHODWH the brightness of a star to its luminosity and distance from the observer. 131Dot Point Page  'HVFULEHD+HUW]VSUXQJ5XVVHOO  GLDJUDPDVWKHJUDSKRIDVWDU¶V luminosity against its colour or surface temperature. 133  8VHWKH+HUW]VSUXQJ5XVVHOOGLDJUDP to examine the variety of star groups  LQFOXGLQJ0DLQ6HTXHQFHUHGJLDQWV and white dwarfs. 134 3.7 Identify energy sources characteristic of each star group including Main  6HTXHQFHUHGJLDQWVDQGZKLWHGZDUIV  4. The Sun 138 4.1 Identify that energy may be released from the nuclei of atoms. 138 4.2 Describe the nature of emissions from the nuclei of atoms as radiation of alpha and beta particles and gamma rays in terms of ionising power, penetrating power, effect of magnetic  ¿HOGHIIHFWRIHOHFWULF¿HOG   3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWR compare the penetrating power of alpha, beta and gamma radiation. 139 4.4 Identify the nature of emissions reaching Earth from the Sun. 140 4.5 Describe the particulate nature of the solar winds. 141 4.6 Outline the cyclic nature of sunspot activity and its impact on Earth through solar winds. 141 4.7 Describe sunspots as representing regions of strong magnetic activity and lower temperature. 142 4.8 Assess the effect of sunspot activity  RQ(DUWK¶VSRZHUJULGDQGVDWHOOLWH communications. 143 Answers to The Cosmic Engine 179 The Cosmic Engine Dot Point Preliminary Physics xiii The Cosmic Engine Science Press

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The Cosmic Engine xiv Dot Point Preliminary Physics Science Press

Dot Point Preliminary Physics 1 Moving About Science Press DOT POINT Moving About

Moving About 2 Dot Point Preliminary Physics Science Press 1. Vehicles do not typically travel at a constant speed. 1.1 Identify that a typical journey involves speed changes. 1.1.1 Describe two speed changes which occur during typical journeys in a car and state one reason for each change. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.2 Distinguish between the average and instantaneous speed of vehicles and other bodies. 1.2.1 Compare average and instantaneous speed. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.3 Distinguish between scalar and vector quantities in equations. 1.3.1 &RPSDUHVFDODUDQGYHFWRUTXDQWLWLHV ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.3.2 &RPSOHWHWKHWDEOHE\LGHQWLI\LQJ¿YHH[DPSOHVHDFKRIVFDODUDQGYHFWRUTXDQWLWLHV Scalar quantities Vector quantities 1.3.3 Compare the distance travelled by an object with its displacement. 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Dot Point Preliminary Physics 3 Moving About Science Press 1.3.4 Three objects travel from X to Y by three different roads as shown in the diagram. Y is due east of X. X Y Road 1 = 75 km Road 3 = 150 km Road 2 = 50 km Use the information to complete the table. Object travelling by Distance travelled (km) Displacement (km) Road 1 Road 2 Road 3 1.3.5 Clarify the idea of expressing direction of travel as a bearing. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.3.6 The diagram shows the paths taken by four wombats as they came out of their burrow to search for food. The diagram is drawn to scale where 1 cm = 10 m. Wombat 1 Wombat 2 Wombat 3 Wombat 4 N Ç Use the information to complete the table. Wombat Distance travelled (m)Displacement (m) (directions as compass readings)Displacement (m) (directions as bearing) 1 2 3 4

Moving About 4 Dot Point Preliminary Physics Science Press  'H¿QHDYHUDJHYHORFLW\DV av rt 1.4.1 ,GHQWLI\WKHTXDQWLW\UHSUHVHQWHGE\
ûrLQWKHDERYHHTXDWLRQ ............................................................................................................................................................................................................................... 1.4.2 'H¿QHWKLVTXDQWLW\ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.5 Compare instantaneous and average speed with instantaneous and average velocity. 1.5.1 :ULWHDQHTXDWLRQ\RXFRXOGXVHWR¿QGWKHDYHUDJHVSHHGRIDQREMHFW ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.5.2 ([SODLQKRZWKLVHTXDWLRQGLIIHUVIURPWKHRQHJLYHQLQDERYH ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.5.3 Identify the essential difference between instantaneous speed and instantaneous velocity. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.5.4 Identify the essential difference between average speed and average velocity. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.5.5 A car takes 2.5 hours to travel along the 150 km road from X and Y as shown in the diagram at a constant speed of 60 kph. X and Y are 120 km apart. X P Q Y N

Dot Point Preliminary Physics 5 Moving About Science Press D  &RPSDUHWKHFDU¶VLQVWDQWDQHRXVVSHHGDWSRLQWV3DQG4 ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... E  &RPSDUHWKHFDU¶VLQVWDQWDQHRXVYHORFLW\DWSRLQWV3DQG4 ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... F  &DOFXODWHWKHFDU¶VDYHUDJHVSHHGIRUWKHMRXUQH\ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... G  &DOFXODWHWKHFDU¶VDYHUDJHYHORFLW\IRUWKHMRXUQH\ ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  6ROYHSUREOHPVDQGDQDO\VHLQIRUPDWLRQXVLQJ av rt 1.6.1 A swimmer dives from the blocks into the pool and races 50 m to the other end of the pool. This takes her 32.6 s. (a) Calculate her average speed. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) Calculate her average velocity. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.6.2 /DWHULQWKHPHHWWKHVDPHVZLPPHUVZLPVLQWKHPHYHQW7KLVWDNHVKHUV (a) Calculate her average speed. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) Calculate her average velocity. ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Moving About 6 Dot Point Preliminary Physics Science Press 1.6.3 Consider three cars travelling from X to Y along three roads shown. Y is due east of X. X Y Road 1 = 120 km Road 3 = 200 km Road 2 = 90 km Use this information to complete the table. Car travelling byDistance travelled (km)Displacement (km)Time taken (hr)Average speed of cars (kph)Average velocity of cars (kph) Road 1 3.0 Road 2 2.0 Road 3 5.0  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWRPHDVXUHWKHDYHUDJHVSHHGRIDQREMHFW 1.7.1 In an experiment, a ball was rolled down a ramp from rest, from various starting positions as shown in the diagram. The results of the experiment are shown in the table. P Q R S T Starting positionDistance up the slope (m)Time to roll down slope (s)Average time to roll down slope (s)Average speed down slope (m s –1)Average speed squared (m 2 s–2) P 1.0 0.64 0.65 0.63 Q 1.5 0.76 0.79 0.79 R 2.0 0.92 0.91 0.87 S 2.5 1.03 0.99 1.01 T 3.0 1.14 1.09 1.10 (a) Complete the table by calculating values for the missing data (to 2 decimal places). (b) If you were to draw a graph to show the relationship between the distance the object started up the slope and its average speed as it rolled down the slope, identify the: independent variable .............................................................................................................................................................. dependent variable ..................................................................................................................................................................

Dot Point Preliminary Physics 7 Moving About Science Press (c) Draw this graph. (d) What conclusion can be made from this graph? ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ (e) Explain your answer. ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ (f) Calculate appropriate values and write them in the last column of the results table and then use these to draw another graph which will enable you to make a conclusion for the experiment. (g) Write your conclusion for the experiment based on this second graph. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. .............................................................................................................................. (h) Use your graph to predict the average speed of the ball if it was rolled down the slope from a 1.25 m starting position. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Moving About 8 Dot Point Preliminary Physics Science Press 1.8 Present information graphically of displacement vs. time for objects with uniform linear velocity. 1.8.1 Consider the following graph representing the motion of a car. (a) How far did the car travel in the ¿UVWV" ....................................................................................................... (b) Determine its change in displacement. ....................................................................................................... (c) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Determine the velocity of the car at time 8 s. ............................................................................................................................................................................................................................... (e) Predict the velocity of the car at time 30 s. ............................................................................................................................................................................................................................... 1.8.2 Consider the following graph representing the motion of a car. (a) How far did the car travel in the ¿UVWV" ...................................................................................................... (b) Determine its change in displacement. ...................................................................................................... (c) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Determine the velocity of the car at time 8 s. ............................................................................................................................................................................................................................... (e) Describe the journey of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 0 5 10 15 20 0 5 10 15 20 Time (s) Displacement (m north) 0 5 10 15 20 25 0 5 10 15 20 Time (s) Displacement (m north)

Dot Point Preliminary Physics 9 Moving About Science Press 1.8.3 Consider the following graph representing the motion of a car. D  +RZIDUGLGWKHFDUWUDYHOLQWKH¿UVW 10 s? .................................................................................................. (b) Calculate the average speed of the car. .................................................................................................. (c) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Determine its displacement after 16 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (e) Determine the velocity of the car at time 8 s. ...............................................................................................................................................................................................................................  3UHVHQWLQIRUPDWLRQJUDSKLFDOO\RIGLVSODFHPHQWYVWLPHIRUREMHFWVZLWKQRQXQLIRUPOLQHDU velocity. 1.9.1 Consider the following graph representing the motion of a car. D  +RZIDUGLGLWWUDYHOLQWKH¿UVWV" .................................................................................................. (b) Determine its total displacement. .................................................................................................. (c) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Determine the velocity of the car at time 12.5 s. ............................................................................................................................................................................................................................... (e) Describe the journey of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... -20 -100 10 20 5101520 Time (s) Displacement (m north) 0 10 20 30 40 50 60 0 5 10 15 20 Time (s) Displacement (m north)

Moving About 10 Dot Point Preliminary Physics Science Press 1.9.2 Consider the following graph representing the motion of a car. D  +RZIDUGLGWKHFDUWUDYHOLQWKH¿UVWV"  .................................................................................................. (b) Determine its total displacement. .................................................................................................. (c) Calculate the average speed of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (e) Determine the velocity of the car at time 3 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.9.3 Consider the following graph representing the motion of a car. D  +RZIDUGLGWKHFDUWUDYHOLQWKH¿UVW 12 s? .................................................................................................. (b) Determine its total displacement. .................................................................................................. (c) Calculate the average speed of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (e) Determine the velocity of the car at time 15 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... -40 -30 -20 -100 10 20 30 40 5101520 Time (s) Displacement (m north) -60 -40 -200 20 40 60 80 5101520 Time (s) Displacement (m north)

Dot Point Preliminary Physics 11 Moving About Science Press 1.10 Present information graphically of velocity vs. time for objects with uniform linear velocity. 1.10.1 Consider the following graph representing the motion of a car. (a) How far did the car travel in 20 s? ........................................................................................ (b) Find its displacement after 10 s. ........................................................................................ (c) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the acceleration of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.10.2 Consider the following graphs representing the motion of four cars. -20 -15 -10-50 5 10 15 20 10 15 20 Time (s) Velocity (m/s north) A B C D 5 Use this information to complete the table. CarAverage speed (m s –1)Average velocity (m s –1)Acceleration (m s –2)Displacement after 10 s A B C D -18 -12-60 6 12 18 5101520 Time (s) Velocity (m/s east)

Moving About 12 Dot Point Preliminary Physics Science Press  3UHVHQWLQIRUPDWLRQJUDSKLFDOO\RIYHORFLW\YVWLPHIRUREMHFWVZLWKQRQXQLIRUPOLQHDUYHORFLW\ 1.11.1 Consider the following graph representing the motion of a car. (a) How far did the car travel in 20 s? ..................................................................................................... (b) Calculate the average velocity of the car. ..................................................................................................... (c) Calculate the acceleration of the car at time 12 s. ..................................................................................................... ..................................................................................................... ..................................................................................................... (d) Calculate the average acceleration of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 1.11.2 Consider the following graph representing the motion of a car. (a) How far did the car travel in 20 s? ...................................................................................................... (b) Calculate its displacement at time 20 s. ...................................................................................................... (c) Calculate the average speed of the car. ...................................................................................................... ...................................................................................................... ...................................................................................................... (d) Calculate the average velocity of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (e) Determine the acceleration of the car at times 3, 7 and 16 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 0 10 20 30 40 50 60 0 5 10 15 20 Time (s) Velocity (m/s north) -10-50 5 10 15 0 5 10 15 20 Time (s) Velocity (m/s south)

Dot Point Preliminary Physics 13 Moving About Science Press 2. An analysis of the external forces on vehicles helps us understand the effects of acceleration and deceleration. 2.1 Describe the motion of one body relative to another. 2.1.1 Object X is moving east at 30 m s –1. Object Y is moving west at 25 m s –1. Object Z is moving east at 15 m s –1. Calculate the velocity of: (a) X relative to Y ........................................................................................................................................................................... (b) X relative to Z ........................................................................................................................................................................... (c) Y relative to X ........................................................................................................................................................................... (d) Y relative to Z ............................................................................................................................................................................ (e) Z relative to X ........................................................................................................................................................................... (f) Z relative to Y ............................................................................................................................................................................ 2.1.2 From your answers above, identify the relationship between the velocity of object A relative to object B and the velocity of object B relative to object A. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.1.3 A person can row a boat at 1.75 m s –1LQVWLOOZDWHU+HURZVRQDULYHUZKLFKÀRZVDW 0.45 m s –1. Calculate the velocity of the person relative to the banks of the river if he rows: D  ZLWKWKHÀRZ ............................................................................................................................................................................... E  DJDLQVWWKHÀRZ ......................................................................................................................................................................... Calculate the velocity of the boat relative to the water if he rows: F  ZLWKWKHÀRZ ............................................................................................................................................................................... G  DJDLQVWWKHÀRZ ......................................................................................................................................................................... 2.2 Identify the usefulness of using vector diagrams to assist in solving problems. 2.2.1 Object X is moving east at 24 m s –1. Object Y is moving north at 18 m s –1. With the aid of an appropriate vector diagram, calculate the velocity of: (a) X relative to Y ........................................................................ ........................................................................ ........................................................................ ........................................................................ ........................................................................ ........................................................................ ........................................................................

Moving About 14 Dot Point Preliminary Physics Science Press (b) Y relative to X ........................................................................ ........................................................................ ........................................................................ ........................................................................ ........................................................................ ........................................................................ ........................................................................ ........................................................................ 2.3 Explain the need for a net external force to act in order to change the velocity of an object. 2.3.1 5HFDOO1HZWRQ¶V)LUVW/DZRI0RWLRQ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.3.2 *LYHDQH[DPSOHRI1HZWRQ¶V)LUVW/DZRI0RWLRQ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.3.3 Describe a situation where an object is travelling with constant speed and yet its velocity is constantly changing. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.3.4 Describe the force acting on the object in 2.3.3 above. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.4 Describe the actions that must be taken for a vehicle to change direction, speed up and slow down. 2.4.1 Identify what is needed to change the direction or speed of an object. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.4.2 What is an object doing if its speed is changing? ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Dot Point Preliminary Physics 15 Moving About Science Press 2.4.3 &ODULI\WKHWHUPVµSRVLWLYH¶DQGµQHJDWLYH¶IRUFHDVWKH\DUHXVHGLQ3K\VLFV ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.5 Describe the typical effects of external forces on bodies including friction and air resistance. 2.5.1 A car travels along a straight road at constant speed. Draw a diagram to show all the forces acting on it. 2.5.2 Describe what each of these forces does to the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.5.3 What is the net force on the car? Explain how you determine this. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.6 Analyse the effects of external forces operating on a vehicle. 2.6.1 Identify three changes a force acting on a vehicle can cause to its motion. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  'H¿QHDYHUDJHDFFHOHUDWLRQDV a av =
ûv/
ût = (v – u)/t 2.7.1 'H¿QHDFFHOHUDWLRQ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.7.2 A force acts on a car for 4.0 s to increase its velocity from 5 m s –1 to 25 m s –1. Calculate the acceleration of the car. ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Moving About 16 Dot Point Preliminary Physics Science Press 2.7.3 A car accelerates at 4.0 m s –2IRUV&DOFXODWHLWV¿QDOYHORFLW\ (a) if its initial velocity was 2.0 m s –1 in the same direction as the force ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) if its initial velocity was 3.5 m s –1 in the opposite direction to the force ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  *DWKHU¿UVWKDQGLQIRUPDWLRQDERXWGLIIHUHQWVLWXDWLRQVZKHUHDFFHOHUDWLRQLVSRVLWLYHDQG negative. 2.8.1 &ODULI\WKHFRQFHSWVRIµSRVLWLYH¶DQGµQHJDWLYH¶DFFHOHUDWLRQV ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.8.2 Identify three different situations where the acceleration of a car would be considered to be positive. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.8.3 Identify three different situations where the acceleration of a car would be considered to be negative. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  'H¿QHWKHWHUPVPDVVDQGZHLJKWZLWKUHIHUHQFHWRWKHHIIHFWVRIJUDYLW\ 2.9.1 'H¿QHPDVV ............................................................................................................................................................................................................................... 2.9.2 'H¿QHZHLJKW ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Dot Point Preliminary Physics 17 Moving About Science Press 2.9.3 Complete the table by comparing various properties of mass and weight. Mass Weight  2XWOLQHWKHIRUFHVLQYROYHGLQFDXVLQJDFKDQJHLQWKHYHORFLW\RIDYHKLFOHZKHQ 2.10.1 It is coasting on a horizontal surface with no pressure on the accelerator. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.10.2 The car is moving on a horizontal surface with the driver pressing on the accelerator. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.10.3 The car is moving on a horizontal surface with the driver pressing on the brakes. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.10.4 The vehicle is passing over an icy patch on a horizontal road. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.10.5 The vehicle is climbing a hill. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.10.6 The vehicle is descending a hill. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Moving About 18 Dot Point Preliminary Physics Science Press 2.10.7 The vehicle is following a curve on a horizontal road. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  ,QWHUSUHW1HZWRQ¶V6HFRQG/DZRI0RWLRQDQGUHODWHLWWRF = ma 2.11.1 5HFDOO1HZWRQ¶V6HFRQG/DZRI0RWLRQ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.11.2 A car is accelerating uniformly along a road. Sketch graphs on the axes below to show the relationships indicated. F t v t r t 2.11.3 Forces act on several cars of different masses to produce identical accelerations. Sketch graphs on the axes below to show the relationships indicated. F m
ûv m
ûr m 2.11.4 Forces act on several cars of different masses to produce identical velocity changes. Sketch graphs on the axes below to show the relationships indicated. F m a m
ûr m

Dot Point Preliminary Physics 19 Moving About Science Press  6ROYHSUREOHPVDQGDQDO\VHLQIRUPDWLRQXVLQJF = ma 2.12.1 Calculate the force acting on a 5.0 kg mass which accelerates for 3.0 s. During this time its velocity changes from 2.5 m s –1 east to 17.5 m s –1 west. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.12.2 A 12 N force acts on a body and accelerates it from rest to 4.5 m s –1 south. This takes 15 s. Calculate the mass of the body. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.12.3 An 80 g object is initially at rest. A 0.16 N force to the north acts on it for 5 s. Calculate: (a) the acceleration produced by the force ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... E  WKH¿QDOYHORFLW\RIWKHREMHFW ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) its displacement after 5 s ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.13 Identify the net force in a wide variety of situations involving modes of transport and explain the consequences of that net force in terms of Newton’s Second law of Motion. Note that the syllabus says ‘a wide variety of situations’. If you have not studied the examples given here in class, then you don’t have to do them. 2.13.1 Consider the two blocks shown in the diagram. They are resting on a surface which provides a frictional force of 0.25 N kg –1. 2.5 kg 5.5 kg 18 N X Y

Moving About 20 Dot Point Preliminary Physics Science Press (a) Calculate the acceleration of the system. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) Calculate the net force on each block. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) Calculate the force block X puts on block Y. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the force block Y puts on block X. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.13.2 Consider the two blocks shown in the diagram. They are resting on a smooth surface. 3.0 kg 6.0 kg 36 N X Y string (a) Calculate the acceleration of the system. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) Calculate the net force on each block. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) Calculate the force tension in the string. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.13.3 Consider the object shown in the diagram. Several forces act on this object which is at rest on a smooth, horizontal surface. 4 kg 26 N 15 N 6 N

Dot Point Preliminary Physics 21 Moving About Science Press (a) Calculate the net force on the object. ......................................................................... ......................................................................... ......................................................................... ......................................................................... ......................................................................... ......................................................................... ......................................................................... ............................................................................................................................................................................................................................... (b) Calculate the acceleration of the object. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) Calculate its velocity after 5.0 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate its displacement after 5 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.13.4 Consider the two blocks shown in the diagram. They are connected by a light string over a frictionless pulley. D  /DEHODOOWKHIRUFHVDFWLQJLQWKLVSXOOH\V\VWHP (b) Calculate the acceleration of the system. .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... (c) Calculate the net force on each block. .................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the tension in the string connecting the blocks. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2 kg 4 kg X Y

Moving About 22 Dot Point Preliminary Physics Science Press 2.13.5 Consider the two blocks shown in the diagram. They are connected by a light string over a frictionless pulley. Block X is resting on a smooth surface. D  /DEHODOOWKHIRUFHVDFWLQJLQ this pulley system. (b) Calculate the acceleration of the system. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) Calculate the net force on each block. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the tension in the string connecting the blocks. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.13.6 A 3 kg mass is resting on a Newton balance in an elevator. Complete the table to show the reading on the balance in each of the following situations. Movement of elevator Reading on Newton balance (a) Stationary (b) Moving up at 2.0 m s –1 (c) Moving down at 2.0 m s –1 (d) Moving up at 2.0 m s –2 (e) Moving down at 2.0 m s –2 X Y 2 kg 5 kg

Dot Point Preliminary Physics 23 Moving About Science Press 2.13.7 Two masses are connected by a string and are hanging from the ceiling of an elevator as shown. Complete the table to show the tensions in each string in the following situations. Movement of elevatorTension in String 1 (N)Tension in String 2 (N) (a) Stationary (b) Moving up at 3.0 m s –1 (c) Moving down at 3.0 m s –1 (d) Moving up at 3.0 m s –2 (e) Moving down at 3.0 m s –2 2.13.8 A ball is hanging by a string from the ceiling of a bus. Describe the motion of the bus when the string is: (a) hanging straight down ............................................................................................................................................................................................................................... (b) hanging down towards the rear of the bus ............................................................................................................................................................................................................................... (c) hanging down towards the front of the bus ............................................................................................................................................................................................................................... 2.13.9 A 3.0 kg ball is hanging by a string from the ceiling of a bus as shown in the diagram. D  /DEHOWKHIRUFHVDFWLQJRQWKHEDOO (b) Using an appropriate vector diagram, calculate the tension in the string when the ball is in the position shown. ..................................................................................................................................................................... ..................................................................................................................................................................... ..................................................................................................................................................................... ..................................................................................................................................................................... (c) Calculate the acceleration of the bus. .............................................................................................................................................................................................................................. .............................................................................................................................................................................................................................. .............................................................................................................................................................................................................................. .............................................................................................................................................................................................................................. (d) See over page. String 1 4 kg String 2 6 kg 10° 3 kg ball

Moving About 24 Dot Point Preliminary Physics Science Press (d) At what angle would the ball and string hang if the bus was braking at 2.5 m s –2? ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. ............................................................................................................................................. .............................................................................................................................................  6ROYHSUREOHPVDQGDQDO\VHLQIRUPDWLRQLQYROYLQJF = mv 2/r for vehicles travelling around curves. 2.14.1 Two 60 kg boys on 20 kg bikes are riding at 15 m s –1 directly towards a wall which is 30 m from them. X continues towards the wall, but slams on his brakes applying a 400 N force. Y does not put on his brakes, but turns his bike with the same force in a circular path in the hope of not hitting the wall. Analyse this information to determine whether or not the boys hit the wall. For X For Y ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... .......................................................................................................... ......................................................................................................... ..........................................................................................................

Dot Point Preliminary Physics 25 Moving About Science Press 2.14.2 A toy racing car of mass 150 g is racing around a circular track of diameter 80 cm. It takes 8.4 s to do one lap of the track. Calculate: (a) the speed of the car ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (a) the acceleration of the car ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) the centripetal force acting on the car ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 2.14.3 A 1500 kg racing car goes around a circular track of radius 200 m at a constant speed of 270 kph. (a) Calculate the speed of the car in m s –1. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) Calculate the acceleration of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) What force holds the car to the road as it speeds around this corner. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the value of this force. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (e) State the direction this force acts. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (f) Predict the value of this force if the speed of the car was to halve. ...............................................................................................................................................................................................................................

Moving About 26 Dot Point Preliminary Physics Science Press  3HUIRUP¿UVWKDQGLQYHVWLJDWLRQVWRVKRZWKHUHODWLRQVKLSEHWZHHQIRUFHPDVVDQGDFFHOHUDWLRQ 2.15.1 Experiment 1 In this experiment, a trolley of mass 1.5 kg was placed on the bench accelerated by a force attached to it by a string, which passed over a pulley. The mass of the trolley was kept constant and different forces used to accelerate it from rest across the bench top. The time it took the trolley to travel 1.0 m across the benchtop was measured. The results are shown in the table. Run Accelerating Force (N) Time to travel 1.0 m (s)Initial speed of trolley (m s –1)Average speed of trolley (m s –1)Final speed of trolley (m s –1)Acceleration of trolley (m s –2) 1 1 F 0.89 2 2 F 0.63 3 3 F 0.52 4 4 F 0.45 5 5 F 0.40 (a) Complete the table by calculating values for all missing data. (b) Draw a graph to show the relationship between the force and acceleration produced. (Place force on the yD[LV (c) Use your graph to write a conclusion for the experiment. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... Trolley Pulley Mass

Dot Point Preliminary Physics 27 Moving About Science Press 2.15.2 Experiment 2 The students did another experiment using the same apparatus. This time they kept the accelerating force constant, and changed the mass of the trolley. They measured how long it took the trolley to move 1.0 m across the benchtop. RunTrolley mass (kg)Time to travel 1.0 m (s)Initial speed of trolley (m s –1)Average speed of trolley (m s –1)Final speed of trolley (m s –1)Acceleration of trolley (m s –2)(Acceleration) –1 1 1.0 1.83 2 2.0 2.58 3 3.0 3.16 4 4.0 3.65 5 5.0 4.08 (a) Complete the table of results by calculating values for all missing TXDQWLWLHV (b) Graph mass vs. (acceleration) –1. (c) Use your graph to write a conclusion for the experiment. ........................................................................................................... ........................................................................................................... ........................................................................................................... ............................................................................................................................................................................................................................... Combining your conclusions for Experiments 1 and 2 G  8VHWKHFRQFOXVLRQV\RXKDYHZULWWHQWRZULWHDPDWKHPDWLFDOHTXDWLRQZKLFKVKRZVWKH relationship between the mass of an object, the force acting on it, and the acceleration the force produces. ............................................................................................................................................................................................................................... H  8VHWKHUHVXOWVRIWKHH[SHULPHQWVWR¿QGWKHYDOXHRIWKHDFFHOHUDWLQJIRUFHVLQWKHWZR experiments above. Experiment 1 ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... Experiment 2 ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Moving About 28 Dot Point Preliminary Physics Science Press 2.16 Solve problems using vector diagrams to determine resultant velocity, acceleration and force. 2.16.1 A 2.5 kg object moving at 5.0 m s –1 east is acted upon by a force which changes its velocity to 12 m s –1 south over a period of 4 s. By drawing an appropriate vector diagram, calculate: (a) the change in velocity of the object ............................................................................................................................. ............................................................................................................................. (b) the acceleration of the object ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. (c) the force that acted on the object ............................................................................................................................. ............................................................................................................................. 2.16.2 The velocity of an object changes from 6.0 m s –1 west to 8.0 m s –1 north when a force of 12 N acts on it for 1.25 s. By drawing an appropriate vector diagram, calculate: (a) the change in velocity of the object ............................................................................................................................. ............................................................................................................................. (b) the acceleration of the object ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. ............................................................................................................................. (c) the direction of the force that acted on the object ............................................................................................................................. ............................................................................................................................. (d) the mass of the object ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Dot Point Preliminary Physics 29 Moving About Science Press  3HUIRUPD¿UVWKDQGLQYHVWLJDWLRQWRGHPRQVWUDWHYHFWRUDGGLWLRQDQGVXEWUDFWLRQ 2.17.1 A group of students set up the following apparatus to investigate the addition of vectors. They hung masses on mass carriers to produce forces F 1 and F 2 on the ends of a long string, then placed a third mass carrier and masses, F 3 on the string between the pulleys. They adjusted WKHPDVVHVRQHDFKFDUULHUXQWLOWKHV\VWHPZDVLQHTXLOLEULXPWKHQPHDVXUHGDQJOH. Their results for three sets of forces are shown in the table. F1 F2 F3  60 g 90 g 132 g 59° 40 g 70 g 95 g 68° 45 g 55 g 70 g 93° By drawing appropriate vector diagrams, show that these results are consistent with F 3 being the resultant of F 1 and F 2. F1 F3 F2 

Moving About 30 Dot Point Preliminary Physics Science Press 3. Moving vehicles have kinetic energy and energy transformations are an important aspect in understanding motion. 3.1 Identify that a moving object possesses kinetic energy and that work done on that object can increase that energy. 3.1.1 Explain, in terms of the law of conservation of energy, the relationship between the work done on a falling object and its kinetic energy. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 3.2 Solve problems and analyse information to determine the kinetic energy of vehicles and the ZRUNGRQHXVLQJ E k = ½mv 2 and W = Fs 3.2.1 A 12 kg car, at rest, is acted upon by a force acting towards the north, for 5 s. This changes its kinetic energy by 2400 J. (a) Calculate the work done on the object by the force. ............................................................................................................................................................................................................................... E  &DOFXODWHWKH¿QDOYHORFLW\RIWKHREMHFW ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) Calculate how far the object moves while the force is acting on it. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) Calculate the acceleration of the object. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (e) Calculate the magnitude of the force acting on the object. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Dot Point Preliminary Physics 31 Moving About Science Press 3.2.2 If the car in Question 3.2.1 had been moving at 10 m s –1 south initially, and the same force acted on it for the same time, calculate: (a) the initial kinetic energy of the car ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... E  WKH¿QDOYHORFLW\RIWKHFDU ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... F  WKH¿QDONLQHWLFHQHUJ\RIWKHFDU ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) the displacement of the car during the 5 seconds ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... H  *LYHQWKDWWKHZRUNGRQHLVHTXDOWRWKHFKDQJHLQHQHUJ\RIWKHFDUFDOFXODWHWKHZRUNGRQH on the car by the force. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (f) Account for your answer to (e). ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 3.3 Describe the energy transformations that occur in collisions. 3.3.1 A car of mass 1000 kg is moving at 15 m s –1 when the driver loses control and it runs off the road, slamming into a tree and stopping. (a) Calculate the initial kinetic energy of the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Moving About 32 Dot Point Preliminary Physics Science Press (b) Calculate the kinetic energy of the car after it has hit the tree. ............................................................................................................................................................................................................................... (c) Account for the difference. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 3.4 Analyse information to trace the energy transfers and transformations in collisions leading to irreversible distortions. 3.4.1 Explain the role of each of the following forms of energy in collisions between moving objects. (a) Potential energy of deformation ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) Sound energy ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) Thermal energy ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  'H¿QHWKHODZRIFRQVHUYDWLRQRIHQHUJ\ 3.5.1 Recall the law of conservation of energy. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 3.5.2 A car has kinetic energy before collision and this is changed to the energy forms above during collision. Identify where all this energy ends up. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Dot Point Preliminary Physics 33 Moving About Science Press 4. Change of momentum relates to the forces acting on the vehicle or the driver.  'H¿QHPRPHQWXPDVp = mv 4.1.1 'H¿QHPRPHQWXP ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  'H¿QHLPSXOVHDVI = Ft 4.2.1 'H¿QHLPSXOVH ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 4.2.2 Clarify the relationship between impulse and momentum change. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 4.3 Explain conservation of momentum in terms of Newton’s Third Law. 4.3.1 8VLQJDSSURSULDWHHTXDWLRQVVKRZKRZ1HZWRQ¶V7KLUG/DZFDQEHXVHGWRH[SODLQWKH conservation of momentum during a collision. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  6ROYHSUREOHPVDQGDQDO\VHGDWDXVLQJ p = mv and I = Ft 4.4.1 A model of a 60.0 kg man and one of a 25 kg child were placed in an 1000 kg car and secured with seatbelts. The car was moving at 70.0 kph as it crashed into a brick wall. (a) Predict what would happen to the models during the collision. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Moving About 34 Dot Point Preliminary Physics Science Press (b) Identify the law of Physics you are using in your answer to (a). ............................................................................................................................................................................................................................... (c) Explain how and why the effect on the models would differ if the front section of the car was specially designed to concertina on impact. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) If the collision took 0.2 s, calculate the average force exerted on each model by its seatbelt. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... H  &DOFXODWHWKHVSHHGDWZKLFKHDFKPRGHOZRXOGEHµWKURZQIRUZDUGV¶ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... I  7KHXVHRIWKHSKUDVHµWKURZQIRUZDUGV¶LQ H LVLQFRUUHFW([SODLQZK\ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... J  5HZULWHTXHVWLRQ H PRUHFRUUHFWO\DVIDUDVWKHSK\VLFVLVFRQFHUQHG ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (h) By making appropriate calculations, assess if it would be possible for a mother to nurse a child and protect it from a collision like this. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

Dot Point Preliminary Physics 35 Moving About Science Press 4.4.2 The graph shows how the force acting on a 0.6 kg object changes with time. (a) Calculate the acceleration of the object at t = 5 s. ....................................................................................... ....................................................................................... (b) Calculate the impulse applied to the object during the 5 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... F  &DOFXODWHWKHREMHFW¶VFKDQJHLQVSHHGGXULQJWKHV ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (d) If its initial velocity was 22 m s –1ZHVWFDOFXODWHLWV¿QDOYHORFLW\ ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 4.4.3 A 150 g toy car collides with a padded lounge chair at 0.20 m s –1. The collision takes 0.3 s. The toy car stops after the collision. (a) Calculate the impulse the car applies to the lounge. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) Calculate the impulse the lounge applies to the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) Calculate the average force the car applies to the lounge. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... 0 2 4 6 8 10 012 345 Time (s) Force (N east)

Moving About 36 Dot Point Preliminary Physics Science Press (d) Calculate the average force the lounge applies to the car. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (e) What law are you using to answer Questions (b) and (d)? ............................................................................................................................................................................................................................... 4.4.4 $NJSDVVHQJHULQDFDULVKHOG¿UPO\E\KHUVHDWEHOWGXULQJDFROOLVLRQ7KHVHDWEHOWLQ stopping her, puts an average force of 12 000 N on her for 1.0 x 10 –2 s. Calculate: (a) the impulse of the force ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (b) the impulse of the force if the collision time was 0.1 s. ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... (c) the initial speed of the car ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................  3HUIRUP¿UVWKDQGLQYHVWLJDWLRQVWRDQDO\VHGDWDIRUWKHFKDQJHLQPRPHQWXPGXULQJFROOLVLRQV 4.5.1 The diagrams show the results of a experiment where trolley X, mass 200 g, collided with trolley Y, 300 g. The results were produced using 10 Hz stroboscopic photography. Analyse the results to determine if momentum was conserved. X Y X Y Before collision After collision ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ............................................................................................................................................................................................................................... ...............................................................................................................................................................................................................................

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