Sat力学-运动学.doc

Sat力学运动学
1.Anobjectthat’smovingwithconstantspeedtravelsoncearoundacircularpath.Truestatementsaboutthismotionincludewhichofthefollowing?
A.ThedisplacementiszeroB.Theaveragespeediszero
C.TheaccelerationiszeroD.Noneoftheabove
A
2.Whichofthefollowingmustalwaysbetrue?
1.Ifanobject’saccelerationisconstant,thenitmustmoveinastraightline
2.Ifanobject’saccelerationiszero,thenitsspeedmustremainconstant
3.Ifanobject’sspeedremainsconstant,thenitsaccelerationmustbezero.
A.1and2only
B.1and3only
C.2only
D.3only
E.2and3only
C
3.Abaseballisthrownstraightupward.Whatistheball’saccelerationatitshighestpoint?
A.0
B.(1/2)g,downward
C.g,downward
D.(1/2)g,upward
E.g,upward
C
4.Howlongwouldittakeacar,startingfromrestandacceleratinguniformlyinastraightlineat5m/s,tocoveradistanceof200m?
A.9s
B10.5s
C.12.0s
D.15.5s
E.20.0s
A
5.Arockisdroppedoffacliffandstrikesthegroundwithanimpactvelocityof30m/s.Howhighwasthecliff?
A.15m
B.20m
C.30m
D.45m
E.60m
D
6.Asoccerballatrestontheground,iskickedwithaninitialvelocityof10m/satalaunchangleof30.Calculateitstotalflighttime,assumingthatairresistanceisnegligible.
A.0.5s
B.1s
C.1.7s
D.2s
E.4s
B
7.Astoneisthrownhorizontallywithaninitialspeedof30m/sfromabridge.Findthestone’stotalspeedwhenitentersthewater4secondslater(Ignoreairresistance.)
A.30m/s
B.40m/s
C.50m/s
D.60m/s
E.70m/s
C
8.Whichoneofthefollowingstatementsistrueconcerningthemotionofanidealprojectilelaunchedatanangleof45tothehorizontal?
A.Theaccelerationvectorpointsoppositetothevelocityvectoronthewayupandinthesamedirectionasthevelocityvectoronthewaydown
B.Thespeedatthetopofthetrajectoryiszero.
C.Theobject’stotalspeedremainsconstantduringtheentireflight
D.Thehorizontalspeeddecreasesonthewayupandincreasesonthewaydown
E.Theverticalspeeddecreasesonthewayupandincreasesonthewaydown
E
9.Whichpairofforcescanproducearesultantof15newtons?
A.20N,20N
B.25N,5N
C.5N,5N
D.7N,7N
E.5N,3N
A
10.Astheanglebetweentwoconcurrentforcesincreases,themagnitudeoftheirresultant
A.increasesonly
B.decreasesandthenincreases
C.increasesand