Xinmin_4N_Prelims_2022_Physics_Marking_Scheme.doc

4NAPrelimScience(Physics) Paper 2022Paper 1(20marks)1 2 3 4 5 6 7 8 9 10A C A B C A D A D B11 12 13 14 15 16 17 18 19 20D C D B C B A A A A Paper 2SectionA(14marks)1a NmorNcm [1] 1b Abecauseitisfurther awayfromthehingeofthedoor. [1] Total [2] 2a Usingarubbercreatesabettergripduetofriction. [1]2b Pourhotwateroverthecaponly.Thehotwaterwillexpandthecapasmatter expandswhenheated. [1][1] Total [3] 3ai.3aii. Thespeedofthecar increases.Thespeedofthecarisaconstant. [1][1]3b averagespeed=60000/(40x60)=25m/s [1][1] Total [4] 4a Thewateratthebottomneartheheaterisheatedandexpands.Itbecomeslessdenseandrises.Therelativelydenser cooler wateratthetopwill sink.Convectioncurrentsaresetup. [1] [1]4b Air isapoor conductor of heat.Laggingminimizeheatlostbythehotwatertothesurrounding. [1] 4c Shinysurfacesarepoor emittersof radiation/poor radiatorsof heat. [1] 4d Waterisheatedupfaster. [1] Total [5]

Paper 2SectionB(16marks)5a Vibrationfromthesourcedisplacedtheair particlesnexttoit.Theairparticleswill movecloser andfurther apartfromeachothercontinuously./Aseriesofalternatecompressionsandrarefactionstravelthroughtheairfromthesource. [1][1] 5bi5bii 5biii Thenumber of completewavesproducedinonesecond.wavelength=320/1000=0.32mdistancebtwPtAandD=0.32(3)=0.96m=96cm5.0ms=0.005sfrequency=1/0.005=200Hz [1][1][1][1][1][1] [8] 6a Energycanneitherbecreatednordestroyedinanyprocess.Itcanbeconvertedfromoneformtoanotherbutthetotalamountremainsconstant. [1mforany2pointsstated] [2] 6b h=6cm=0.06mGPE=0.008(10)(0.06)=0.0048J [1][1]6c 0.0048J [1]6d 0.5(0.008)v 2 =0.0048v 2 =1.2v=1.1m/s [1] [1]6e Thereareresistiveforcessuchasfrictiononthetrackandairresistance [1] [8] 7a A:ammeterB:voltmeter [1][1]7b axiscorrectlylabelledwithcorrectintervalsall5pointsplottedclearlywithcrossesstraightlinedrawnthroughthecrossesneatly [1][1][1]7c all5pointsplottedclearlywithcrossesstraightlinedrawnthroughthecrossesneatly [1]7d ResistorYhasalowerresistancethanresistorX. [1][1]

ThegradientforresistorYissmallerthanresistorX./Foreachvalueofcurrent,voltageforresistorYissmaller.(V=RI) Total [8]