SJPO_General_Round_2012

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1、SINGAPOREJUNIORPHYSICSOLYMPIAD2012GENERALROUND1August,20123:00pm–4:30pmTimeAllowed:ONEhourTHIRTYminutesINSTRUCTIONS1.Thispapercontains50multiplechoicequestionsand19printedpages.2.Eachofthequestionsorincompletestatementsisfollowedbyfivesuggestedan-swersorcompletions.Selecttheon

2、ethatisbestineachcaseandthenshadethecorrespondingbubbleontheanswersheet.3.Onlytheanswersheetwillbecollectedattheendofthetest.Answerswrittenanywhereelsewillnotbemarked.4.Use2Bpencilonly.Usinganyothertypeofpencilorpenmayresultinanswersunrecognizablebythemachine.5.Answerallquest

3、ions.MarkswillNOTbedeductedforwronganswers.6.Scientificcalculatorsareallowedinthistest.Graphiccalculatorsarenotallowed.7.Atableofinformationisgiveninpage2.TABLEOFINFORMATION2AccelerationduetogravityatEarthsurface,g=9.80m/sUniversalgasconstant,R=8.31J/(mol·K)−1222Vacuumpermitti

4、vity,0=8.85×10C/(N·m)−7Vacuumpermeability,μ0=4π×10T·m/A−27Atomicmassunit,u=1.66×10kg8Speedoflightinvacuum,c=3.00×10m/s−19Chargeofelectron,e=1.60×10C−34Planck’sconstant,h=6.63×10J·s−31Massofelectron,me=9.11×10kg−27Massofproton,mp=1.67×10kg−23Boltzmannconstant,k=1.38×10J/K23−1

5、Avogadro’snumber,NA=6.02×10mol5Standardatmospherepressure,P0=1.01×10Pa3Densityofwater,ρw=1000kg/m3◦Specificheat(capacity)ofwater,cw=4.19×10J/(kg·C)5Latentheatoffusionofwater,Lf=3.33×10J/kg6Latentheatofvaporizationofwater,Lv=2.26×10J/kg21.Aconstantforceisappliedtoabodythatisalr

6、eadymoving.Theforceisdirectedatanangleof70◦tothedirectionofthebody’svelocity.Whatismostlikelytohappenisthat(A)thebodywillstopmoving.(B)thebodywillmoveinthedirectionoftheforce.(C)thebody’svelocitywillincreaseinmagnitudebutnotchangedirection.(D)thebodywillgraduallychangedirecti

7、onmoreandmoretowardthatoftheforce.(E)thebodywillfirststopmovingandthenmoveinthedirectionoftheforce.¯2.Asphereofmassmissuspendedfromtwostringsofunequallengthasshown.ThetensionsT1andT2inthestringsmustsatisfywhichofthefollowingrelations?(A)T1=T2(B)T1>T2(C)T1

8、=mg3.Acarwithmass105kgstartsfromrest,drivenbyanenginewithuniformpowe