理論力學(xué)智慧樹知到課后章節(jié)答案2023年下長安大學(xué)

理論力學(xué)智慧樹知到課后章節(jié)答案2023年下長安大學(xué)長安大學(xué)

緒論單元測試

Afterthe20thcentury,physicsdividedintotwobranches:modernphysicsandmodernmechanics.（）

A:對B:錯

答案:對

Whoisknownasthe"fatherofmechanics"（）.

A:AristotleB:StevenC:NewtonD:Archimedes

答案:Archimedes

第一章測試

Thereisacoplanarconcurrentforcesystemactingonarigidbody,andtheforcevectorrelationshipoftheforcesisshowninFigure，Itcanbeknownthattheresultantforceoftheforcesystemiszeroandtheforcesystemisinequilibrium.（）

A:錯B:對

答案:錯

Asisshowninthefigure,theforcePonACcanbemovedtoBCaccordingtothetransmissibilityoftheforce.（）

A:對B:錯

答案:錯

Arigidbody,subjectedtoforceswhichareactedontwopoints,iscalledDouble-forceBody.（）

A:錯B:對

答案:錯

andmeansthesame.（）

A:錯B:對

答案:錯

TheFBDshowninthefigureiscorrect.（）

A:錯B:對

答案:錯

第二章測試

Thereisacoplanarconcurrentforcesystemactingonarigidbody,andtheforcevectorrelationshipoftheforcesisshowninFigure，Itcanbeknownthatthereductionoftheforcesystemis（）.

A:acoupleB:aforceandacoupleC:inequilibriumD:aforce

答案:inequilibrium

Asisshowninthefigure,ifthecoupleMactingonACismovedtoBC,themagnitudeofthereactionforcesatA,BandC（）.

A:unchangedatAandB,changedatCB:changedatAandB,unchangedatCC:AllunchangedD:Allchanged

答案:Allunchanged

Themagnitudeanddirectionoftheforcecanbedeterminedbytheanalyticalexpressionoftheforce.（）

A:對B:錯

答案:對

TheweightoftherodABandCDandthefrictionisignored,ifthemomentofthecoupleactingontherodABis,inordertokeepthesystembalanced,themomentofthecoupleactingontherodCDisisshowninthefigure,anditsmomentvalueis（）.

A:B:C:D:

答案:

Asisshowninthefigure,thecoupleMactsontheACrod,themagnitudeofthereactionforceofsupportAis（）.

A:8kNB:4kNC:10kND:5kN

答案:10kN

第三章測試

TakinganytwopointsAandBintheactionplaneoftheconplanarforcesystem,iftheprincipalmomentsoftheforcesystemaboutthesetwopointsarebothzero,theforcesystemcannotbecomposedintoaforce.（）

A:錯B:對

答案:錯

Aconplanarforcesystemcannotbecomposedintoacoupleiftheprincipalmomentoftheforcesystemaboutanypointisequaltozero.（）

A:對B:錯

答案:對

ThearbitraryforcesystemofacertainplaneissimplifiedtopointO,andR'=10N,MO=10N·cmareobtained.Thedirectionsareshowninthefigure.ThenthesimplificationresultofthisforcesystemtopointAis（）.

A:Rˊ=10N，MA=10N·cmB:Rˊ=0，MA=0C:Rˊ=10N，MA=20N·cmD:Rˊ=10N，MA=0

答案:Rˊ=10N，MA=0

AnarbitraryforcesysteminaplaneissimplifiedtopointO,aforceR'andacouplewithcouplemomentMOareobtainedasshowninthefigure,thenthefinalsimplificationresultoftheforcesystemis（）.

A:AresultantcoupleB:AresultantforceatOC:AresultantforceatsomepointontherightofOD:AresultantforceatsomepointontheleftofO

答案:AresultantforceatsomepointontheleftofO

Shownasthefigure,theequilateraltriangleplatewithsidelengthof1misaffectedby,F2=2kN,.Thenthefinalreductionoftheforcesystemis（）.

A:Aresultantforcewithmagnitude2kN,actingatpointA,←B:Aresultantforcewithmagnitude2kN,actingatpointB,→C:Aresultantforcewithmagnitude1kN,actingatpointA,→D:Aresultantforcewithmagnitude1kN,actingatpointA,←

答案:Aresultantforcewithmagnitude1kN,actingatpointA,←

第四章測試

Asshowninthefigure,ifthecompositebeamisbalancedunderthegeneralcoplanarforcesystem,nineindependentbalanceequationscanbelistedifABbar,ACbarandtheentiresystemaretakenastheresearchobjects,right?（）

A:錯B:對

答案:錯

Therearefiveindependentequilibriumequationsforanoncoplanarforcesysteminwhichtheactionlinesoftheforcesareontwoparallelfixedplanes.（）

A:錯B:對

答案:對

Thereareatmostthreeindependentequilibriumequationsforanoncoplanarforcesysteminwhicheachforceactionlineisperpendiculartoafixedplane.（）

A:對B:錯

答案:對

Inthefigure,a=1m,acouplewithamomentofM=10kN·misactedonthestructure,thereactionforceoffixedhingesupportDwithoutregardingtotheweightofeachbaris（）.

A:20kN,→B:10kN,→C:20kN,←D:10kN,←

答案:10kN,→

ThestructureshowninthefigureiscomposedofbarsAB,DEandBD,theweightofeachbarisnotcounted.D,CandBareallhingedconnections,andendAisfixedsupport.Given:q（N/m）,M=qa2（N·m）,P=qa（N）,anddimensionsasshowninfigure.ThentheinternalforceofrodBDis（）.

A:B:C:D:

答案:

第五章測試

TheblockweighsW,andanexternalforceFactsontheblockwiththeactionlineoutsideoftheangleoffriction,asshowninthefigure.Givenθ=25°,angleoffrictionφm=20°,F=W,thentheblockisatrest.（）

A:錯B:對

答案:對

Asshowninthefigure,splitwithasteelwedgeandtheangleoffrictionbetweenthecontactsurfacesisφm.Inordertomakethewedgedonotslipoutaftersplitting,theangleθshouldbe（）.

A:θ≤φmB:θ>2φmC:θ>φmD:θ≤2φm

答案:θ≤2φm

Inthecaseoffriction,theanglebetweenthetotalreactionforceandthenormalreactionforceiscalledtheangleoffriction.（）

A:錯B:對

答案:錯

Asshowninthefigure,givenW=100kN,P=80kN,andthecoefficientofstaticfrictionisfs=0.2,thentheblockwillmoveupward.（）.

A:對B:錯

答案:錯

RectangularcabinetasshowninthefigureweightsG,andcenterofgravityCisinitsgeometriccenter.Thecoefficientofstaticfrictionisfsbetweenthecabinetandtheground.AhorizontalforceFisappliedtothecabinetonright,thentheminimumvalueofFrequiredtomakethecabinetbeinequilibriumis（）.

A:max{Gfs,Ga/2h}B:min{Gfs,Ga/2h}C:min{2Gfs,Ga/h}D:max{2Gfs,Ga/h}

答案:min{Gfs,Ga/2h}

第六章測試

Ifthevelocityofamovingpointwhichisdoingplanecurvilinearmotionisconstant,thevelocityvectorisperpendiculartotheaccelerationvector.（）

A:對B:錯

答案:對

TherightanglerigidbarOABattheinstantshowninthefigurehasω=2rad/sandα=5rad/s2.IfOA=40cm,AB=30cm,thetangentialaccelerationandnormalaccelerationofpointBare（）.

A:200m/s2,250m/s2B:250m/s2,250m/s2C:200m/s2,200m/s2D:250m/s2,200m/s2

答案:250m/s2,200m/s2

Asshowninthefigure,givenAB∥O1O2,AB=O1O2=L,AO1=BO2=r,ABCDisarectangularplate,andAD=BC=b,AO1rodrotatesaroundthefixedaxisO1atauniformangularvelocityω,thenthevelocityandaccelerationofthecenterofgravityC1oftherectangularplateare（）.

A:v=rω/2,a=rω2B:v=rω,a=rω2/2C:v=lω,a=lω2D:v=rω,a=rω2

答案:v=rω,a=rω2

ThegearwithradiusRrotatesaroundthefixedaxisO,anddrivestherackABtomove.Giventhattheangularvelocityofgearisωandtheangularaccelerationofgearisαattheinstantshownasfigure.PointConthegearisincontactwithpointC'ontherack,thentheaccelerationofpointCandtheaccelerationofpointC'are（）.

A:B:C:D:

答案:

ThesquareplateABCDisrotatingaroundafixedaxis,andtherotationalaxisisperpendiculartotheplatesurface.ThevelocityofpointAisvA=10cm/sanditsaccelerationis.Thedirectionsareshowninthefigure.Thentheangularvelocityofthesquareplateis（）.

A:4rad/sB:1rad/sC:2rad/sD:3rad/s

答案:1rad/s

第七章測試

ThewheelwithradiusRrotatesclockwiseaboutaxisOatauniformangularvelocityω,anddrivesrodABtorotateaboutaxisA.TakethecenterofwheelCasmovingpoint，androdABasthereferenceobjecttowhichthemovingreferenceframeisfixedlyattached.Whichofthefollowingstatementsistrue?（）

A:ThetransportpointisontherodAB.B:ThedirectionofthetransportvelocityisperpendiculartoAC.C:TheabsolutemotiontrajectoryisthecirclearoundO.D:TherelativemotiontrajectoryisastraightlineparalleltoAB.

答案:ThedirectionofthetransportvelocityisperpendiculartoAC.;TheabsolutemotiontrajectoryisthecirclearoundO.;TherelativemotiontrajectoryisastraightlineparalleltoAB.

Atthismomentshowninthisfigure,rodOCDrotatesaroundaxisOatanangularvelocity,makingrodABmovealongtheverticaldirection.OC=Lisknown.TakepointAontheABrodasthemovingpoint,andthemovingreferenceframeisfixedontherodOCD.Atthepositionshown,φ=45°,thetransportvelocityofpointAis（）.

A:B:C:D:0

答案:

Asshowninthefigure,,therodrotatesaboutfixedaxisAatauniformangularvelocityω=2rad/s.ThereisasleeveContherodAB,whichishingedwiththerodCD,andallpartsofthemechanismareinthesameplane.ThesleeveCisselectedasthemovingpoint,andtheABrodisthemovingreferenceframe.Whenφ=60°,thetransportvelocityis（）.

A:B:2m/s，alongthehorizontalC:1m/s，alongthehorizontalD:

答案:

Inacrankslidemechanism,thecrankOAwithlengthl=0.2mrotatesanticlockwiseaboutaxisOatauniformangularvelocityof3rad/s.ThecrankendAishingedwiththeslidingblockAwhichcanslidealongthegroovetodrivetheT-shapedslidewayBCforreciprocatingtranslation.Iftheanglebetweenthecrankandtheaxisoftheslideis30°atthisinstant,theaccelerationofT-shapedslidewayBCis（）.

A:B:C:D:

答案:

TakepointBonBCrodasthemovingpoint,andthemovingreferenceframeisfixedtotheflat-bottomcam.Theaccelerationvectorisshowninthefigure.IfthetheoremofcompositionofaccelerationsisprojectedtoOBdirection,writetheprojectionformula,whichofthefollowingequationsiscorrect?（）

A:B:C:D:

答案:

第八章測試

TheequilateraltriangleplatewithsidelengthLmovesinitsownplane.GiventheaccelerationofpointArelativetopointBisaAB,whosemagnitudeisaanddirectionisparalleltoCB,thentheangularvelocityofthetriangleplateatthisinstantis（）.

A:B:C:D:

答案:

Thevelocityoftwoparallelracksarev1=5m/sandv2=2m/s.Thereisagearinthemiddleofthetwotracks.R=0.5m.Theangularvelocityofthegearis（）.

A:2rad/s(clockwise)B:3rad/s(clockwise)C:2rad/s(counterclockwise)D:3rad/s(counterclockwise)

答案:3rad/s(clockwise)

ThinplateBCissupportedbytwoequallengthbarsABandCD,anditmovesinitsownplane.Attheinstantasshowninfigure,ABBC,BCCD.IfbarABrotatesatauniformangularvelocityω,thenatthisinstant（）.

A:B:C:D:

答案:;

Theaccelerationoftheinstantaneouscenterofvelocitiesmayalsobezero.（）

A:錯B:對

答案:錯

Crank-rodmechanismisshowninfigure,known:AB=OA=L,φ1=φ2=φ,uniformangularvelocityω.Theradiusofthewheelisr,anditrollswithoutslippingalongthefixedhorizontalplane.ThentheangularvelocityandangularaccelerationofwheelBare（）.

A:B:C:D:

答案:

第九章測試

ObjectMwithweightP=10N,isplacedonasmoothinclinedplane,whichcanrotateabouttheY-axis.RopelengthL=2m,inclinedangleθ=30°,andtheuniformrotationalspeedn=10r/min,thenthetensionoftheropeis（）.

A:7.68NB:5.68NC:6.68ND:4.68N

答案:6.68N

Iftwoparticleshavethesamemassandareacteduponbythesameforce,theirvelocitiesandaccelerationsareequalatanyinstant.（）

A:錯B:對

答案:錯

Asshowninthefigure,thetrolleymovesupwardalongtheinclinedplanewiththeuniformaccelerationa,andanobjectAwiththemassmisplacedontheflattopofthetrolleytomovewiththetrolley.Inordertopreventtheobjectfromfallingofffromthetrolley,theminimumstaticfrictioncoefficientbetweentheobjectandthetrolleyshouldbe（）.

A:B:C:D:

答案:

Asshowninthefigure,asmallballwithmassmsuspendedbytworopesisatrest.IfropeAiscut,thetensionofropeBatthisinstantis（）.

A:B:C:D:

答案:

ThesmallringslidesfromthetopAofthefixedsmoothhalfcylinderwithoutinitialvelocity,asshowninthefigure,thenthepositionangleφatwhichtheringisdetachedfromthehalfcylinderis（）.

A:58.2°B:45°C:48.2°D:50°

答案:48.2°

第十章測試

ThelengthoftherodABis40cm,theoriginallengthofthespringis20cm,thespringconstantk=200N/m,andthemomentofcoupleM=180Nm.WhentherodABmovesfromthepositionshowninthediagramtothehorizontalpositionA'B,findtheworkoftheelasticforceandtheworkofthecoupleM.（）

A:-1.46J,30πJB:-1.46J,-30πJC:1.46J,30πJD:1.46J,-30πJ

答案:1.46J,-30πJ

Determinethemomentofinertiaofahomogeneousdisk(massm,radiusr)abouttheO-axis,wherethedistancebetweentheO-axisandthemasscenterCise.（）

A:B:C:D:

答案:

ThehomogeneousbarAB,withmassmandlengthl,rotatesaboutaxisAwithangularvelocityω,andaxisAmoveshorizontallywithvelocityv.FindthekineticenergyofbarABatthemomentshowninthefigure.（）

A:B:C:D:

答案:

Ifthependulumisreleasedfromthehorizontalposition,thevelocityofitsbobintheverticalpositionis（）.

A:3.8m/sB:21m/sC:6.9m/sD:14.7m/s

答案:3.8m/s

Thecenterofahomogeneouswheel(massm,radiusr)hasthevelocityv0intheinitialpositionasshowninthefigure.Thewheelrollswithoutslipping.Calculatethevelocityvofitscenterinthepositionshownbythebrokenlines.（）

A:B:C:D:

答案:

第十一章測試

ThesmallballMwithweightQisfixedonathinhomogeneousrodoflengthlandweightP.Theotherendoftherodishingedontheroofofthecarmovingwithv.TherodOMrotatescounterclockwisearoundaxisOatanangularvelocityω.Thenthemagnitudesofthemomentumsoftherodandthesmallballattheinstantshownasfigureare（）.

A:B:C:D:

答案:

Twoidenticalhomogeneousdisksareplacedonasmoothhorizontalplane,andtwosamehorizontalforcesareappliedonthedifferentpositionsofthedisks,respectively,sothatthedisksstarttomovefromrest.ThemasscenterofdiskAmovesfaster.（）

A:錯B:對

答案:錯

WhenAparticleofmassmmovesinacircleataconstantspeedvA=vB=vfrompositionAtopositionB,theimpulseoftheforceactingontheparticleis（）.

A:B:C:D:

答案:

Thefigureshowsacrank-rodmechanismontheplatform,whichiscomposedoftwohomogeneousbarsandaslider.TherodO1Arotatesatauniformangularvelocityωandgiven:O1AweighsP1,ABweighsP2,platformweighsQ,O1A=AB=L.Lett=0,angle=0,andthevelocityofplatformiszero.ExcludingthemassofthesliderBandthefrictionontheground,themotionalequationoftheplatformis（）.

A:B:C:D:

答案:

A

homogeneousrodOArotatesaroundthefixedaxis

O

withconstantangularvelocity

ω.Themassoftherodis

m

anditslengthis

L,thenthemagnitudeofmomentumofthisrodis

mLω/2.

A:錯B:對

答案:對

第十二章測試

AhomogeneousrodOAwithmassmandlengthLrotatesaroundthefixedaxisOatuniformangularspeedω,thenthemagnitudeofangularmomentumofthisrodtoaxisOis（）.

A:mL2ω/4B:mL2ω/3C:mL