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Question Number 3463 by prakash jain last updated on 13/Dec/15
Acarstartsfromrestanduniformlyacceleratesfor1km,travelswithuniformvelocityfor98kmandbrakesandstopaftertravellinganother1km.Considertheaboveexperimentbeingdoneon2differentroads1stroadshashighercoefficientoffrictionforcarforalltypesthan2ndroad.Compareenergyconsumedin2cases,whichoneconsumesmoreenergyandwhy?
Commented by prakash jain last updated on 13/Dec/15
Samecarisusedonbothtracks.Allotherthingsequalonlyfrictionchanges.
Answered by Yozzii last updated on 13/Dec/15
TheenergyWexpendedbyabodymovingagainstfrictionalforcefisW=fdwhered=distancetravelledforwhichfacts.Insituationsofmotionalongaroadwithacertaincoefficientoffrictionμ,ftakesamaximumvalueofμR,whereR=normalreactiononbodybytheroad.∴W=μRd.IfdandRareconstantonly,⇒W∝μ.R=mgbyNewton′s3rdLawofMotionwherem=massofbody,g=accelerationduetogravity(dependentuponplanetwheretheexperimentisheld).Inbothcasesd=constant(100km)andanyvalidcomparisonmusthavetheexperimentperformedwithidenticalcarsonthesametrack,sothatRisconstant.SinceW∝μ,thetrackwithhigherμincurshigherenergyconsumptiononagivencar.
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