大学物理试卷含答案

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1、得分评阅人大学物理试卷一、基础知识题（共4小题，每小题10分，共40分）1.FindtheanglebetweenthetwovectorsA=2i-2^j+3kandB=3i+2j-2kSolutionA-B=ABcos0=ABr+ABv+ABZaayyzzAxBx+AB+AzBz4cos3==——=-0.235AB173=180°-arccos0.235=103.6°2.Supposeyoutrytomoveyourcratefullofequipmentbytyingaropearounditandpullingupwardatana

2、ngleabovethehorizontalontherope.Findtheangleatwhichyouneedtheminimumforcetokeepthecratemovingwithconstantvelocity.(“&=0-44)Solutionmg=N+Fsina[Fcosa=NjUk，(cosa+Pksina)=0da,二mg山cosa+]LLksinor,一sina+以cosQ=0tanoc—jUk=0.44,oc—23.7°1.ItispossibletobankacurvewithradiusRatjustther

3、ightanglesothatacartravelingatacertainspeedvcansafelymaketheturnevenifthereisnofriction.Atwhatangle0shouldthecurvebebanked?Solutiontan/3=v21gRmgtan0=mv2/RP二arctanv2/gR2.Whatisthethermalefficiencyofanenginethatoperatesbytakingnmolesofadiatomicidealgasthroughthecycleofa—b—>c

4、—a?SolutionQ{=nCv(Tb-TJ=n^R^-T^=^RT07Q2=nCm=n寸・(6T°-2TJ=14冰W=p0V0=nRT°wW2"QhQ+@33得分评阅人二、计算题（共2小题，每小题10分，共20分）Aprimitiveyo-yoismadebywrappingastringseveraltimesaroundasolidcylinderwithmassMandradiusR.Youholdtheendofthestringstationarywhilereleasingthecylinderwithnoinitialmo

5、tion.Thestringunwindsbutdocsnotsliporstretchasthecylinderdropsandrotates.Findthetensioninthestringandthespeedofthecenterofmassofthesolidcylinderafterithasdroppedadistanceh.Solution=Ra[Mg-T=Macmi=LmrTR=la2丁1册2T=~Mg,acm=-g2.A50.0-kgwomanstandsupina60>0-kgcanoeoflength5.00m.

6、ShewalksfromapointLOOmfromoneendtoapoint1.00mfromtheotherend.Ifresistancetomotionofthecanoeinthewatercanbeneglected,howfardoesthecanoemoveduringthisprocess?Solution-3x50.0L—50.0+60.0=136(m)mv=MV，ml=ML50.0x(3.00-L)=60.0xLThecanoemoves1.36metersintheoppositedirection.2.A50.0

7、-kgwomanstandsupina60>0-kgcanoeoflength5.00m.ShewalksfromapointLOOmfromoneendtoapoint1.00mfromtheotherend.Ifresistancetomotionofthecanoeinthewatercanbeneglected,howfardoesthecanoemoveduringthisprocess?Solution-3x50.0L—50.0+60.0=136(m)mv=MV，ml=ML50.0x(3.00-L)=60.0xLThecanoe

8、moves1.36metersintheoppositedirection.得分评阅人三、叙述题（10分）Ifawomaninatraincouldwalkdowntheaisl