理論力學(xué)知到章節(jié)答案智慧樹2023年長(zhǎng)安大學(xué)

理論力學(xué)知到章節(jié)測(cè)試答案智慧樹2023年最新長(zhǎng)安大學(xué)緒論單元測(cè)試

Afterthe20thcentury,physicsdividedintotwobranches:modernphysicsandmodernmechanics.（）

參考答案:

對(duì)

Whoisknownasthe"fatherofmechanics"（）.

參考答案:

Archimedes

第一章測(cè)試

Thereisacoplanarconcurrentforcesystemactingonarigidbody,andtheforcevectorrelationshipoftheforcesisshowninFigure，Itcanbeknownthattheresultantforceoftheforcesystemiszeroandtheforcesystemisinequilibrium.（）

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錯(cuò)

Asisshowninthefigure,theforcePonACcanbemovedtoBCaccordingtothetransmissibilityoftheforce.（）

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錯(cuò)

Arigidbody,subjectedtoforceswhichareactedontwopoints,iscalledDouble-forceBody.（）

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錯(cuò)

andmeansthesame.（）

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錯(cuò)

TheFBDshowninthefigureiscorrect.（）

參考答案:

錯(cuò)

第二章測(cè)試

Thereisacoplanarconcurrentforcesystemactingonarigidbody,andtheforcevectorrelationshipoftheforcesisshowninFigure，Itcanbeknownthatthereductionoftheforcesystemis（）.

參考答案:

inequilibrium

Asisshowninthefigure,ifthecoupleMactingonACismovedtoBC,themagnitudeofthereactionforcesatA,BandC（）.

參考答案:

Allunchanged

Themagnitudeanddirectionoftheforcecanbedeterminedbytheanalyticalexpressionoftheforce.（）

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對(duì)

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

參考答案:

Asisshowninthefigure,thecoupleMactsontheACrod,themagnitudeofthereactionforceofsupportAis（）.

參考答案:

10kN

第三章測(cè)試

TakinganytwopointsAandBintheactionplaneoftheconplanarforcesystem,iftheprincipalmomentsoftheforcesystemaboutthesetwopointsarebothzero,theforcesystemcannotbecomposedintoaforce.（）

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錯(cuò)

Aconplanarforcesystemcannotbecomposedintoacoupleiftheprincipalmomentoftheforcesystemaboutanypointisequaltozero.（）

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對(duì)

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

參考答案:

Rˊ=10N，MA=0

AnarbitraryforcesysteminaplaneissimplifiedtopointO,aforceR'andacouplewithcouplemomentMOareobtainedasshowninthefigure,thenthefinalsimplificationresultoftheforcesystemis（）.

參考答案:

AresultantforceatsomepointontheleftofO

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

參考答案:

Aresultantforcewithmagnitude1kN,actingatpointA,←

第四章測(cè)試

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

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錯(cuò)

Therearefiveindependentequilibriumequationsforanoncoplanarforcesysteminwhichtheactionlinesoftheforcesareontwoparallelfixedplanes.（）

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對(duì)

Thereareatmostthreeindependentequilibriumequationsforanoncoplanarforcesysteminwhicheachforceactionlineisperpendiculartoafixedplane.（）

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對(duì)

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

參考答案:

10kN,→

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

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第五章測(cè)試

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

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對(duì)

Asshowninthefigure,splitwithasteelwedgeandtheangleoffrictionbetweenthecontactsurfacesisφm.Inordertomakethewedgedonotslipoutaftersplitting,theangleθshouldbe（）.

參考答案:

θ≤2φm

Inthecaseoffriction,theanglebetweenthetotalreactionforceandthenormalreactionforceiscalledtheangleoffriction.（）

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錯(cuò)

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

參考答案:

錯(cuò)

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

參考答案:

min{Gfs,Ga/2h}

第六章測(cè)試

Ifthevelocityofamovingpointwhichisdoingplanecurvilinearmotionisconstant,thevelocityvectorisperpendiculartotheaccelerationvector.（）

參考答案:

對(duì)

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

參考答案:

250m/s2,200m/s2

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

參考答案:

v=rω,a=rω2

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

參考答案:

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

參考答案:

1rad/s

第七章測(cè)試

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

參考答案:

ThedirectionofthetransportvelocityisperpendiculartoAC.;TheabsolutemotiontrajectoryisthecirclearoundO.;TherelativemotiontrajectoryisastraightlineparalleltoAB.

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

參考答案:

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

參考答案:

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

參考答案:

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

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第八章測(cè)試

TheequilateraltriangleplatewithsidelengthLmovesinitsownplane.GiventheaccelerationofpointArelativetopointBisaAB,whosemagnitudeisaanddirectionisparalleltoCB,thentheangularvelocityofthetriangleplateatthisinstantis（）.

參考答案:

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

參考答案:

3rad/s(clockwise)

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

參考答案:

;

Theaccelerationoftheinstantaneouscenterofvelocitiesmayalsobezero.（）

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錯(cuò)

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

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第九章測(cè)試

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

參考答案:

6.68N

Iftwoparticleshavethesamemassandareacteduponbythesameforce,theirvelocitiesandaccelerationsareequalatanyinstant.（）

參考答案:

錯(cuò)

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

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Asshowninthefigure,asmallballwithmassmsuspendedbytworopesisatrest.IfropeAiscut,thetensionofropeBatthisinstantis（）.

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ThesmallringslidesfromthetopAofthefixedsmoothhalfcylinderwithoutinitialvelocity,asshowninthefigure,thenthepositionangleφatwhichtheringisdetachedfromthehalfcylinderis（）.

參考答案:

48.2°

第十章測(cè)試

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

參考答案:

1.46J,-30πJ

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

參考答案:

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

參考答案:

Ifthependulumisreleasedfromthehorizontalposition,thevelocityofitsbobintheverticalpositionis（）.

參考答案:

3.8m/s

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

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第十一章測(cè)試

ThesmallballMwithweightQisfixedonathinhomogeneousrodoflengthlandweightP.Theotherendoftherodishingedontheroofofthecarmovingwithv.TherodOMrotatescounterclockwisearoundaxisOatanangularvelocityω.Thenthemagnitudesofthemomentumsoftherodandthesmallballattheinstantshownasfigureare（）.

參考答案:

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

參考答案:

錯(cuò)

WhenAparticleofmassmmovesinacircleataconstantspeedvA=vB=vfrompositionAtopositionB,theimpulseoftheforceactingontheparticleis（）.

參考答案:

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

參考答案:

A

homogeneousrodOArotatesaroundthefixedaxis

O

withconstantangularvelocity

ω.Themassoftherodis

m

anditslengthis

L,thenthemagnitudeofmomentumofthisrodis

mLω/2.

參考答案:

對(duì)

第十二章測(cè)試

AhomogeneousrodOAwithmassmandlengthLrotatesaroundthefixedaxisOatuniformangularspeedω,thenthemagnitudeofangularmomentumofthisrodtoaxisOis（）.

參考答案:

mL2ω/3

Thetriangleplaterotatesataconstantangularv