MOMENTUM - SchoolWorld an Edline Solution

《MOMENTUM - SchoolWorld an Edline Solution》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、MOMENTUM&COLLISIONSLinearMomentumMovingobjectshavemomentumVectorquantityPointsinthesamedirectionasthevelocityvectorMomentum:EqualstheproductofanobjectsmassandvelocityProportionaltomassandvelocityp=mvp=momentum(kg*m/s)m=mass(kg)v=velocity(m/s)TAXIPROBLEMWhatisthetaxicab’smomentum?*Massofthetaxi=

2、53kg*Velocityofthetaxi=1.2m/sAnswer:p=mvp=(53kg)(1.2m/s)p=63.6kg*m/stotheleftv=1.2m/sp=63.6kg*m/sMomentum&Newton’s2ndLawNewton’s2ndLawΣF=ma=m(Δv/Δt)ΣF=m(Δv/Δt)Momentump=mvm=p/vΣF=(p/v)(Δv/Δt)ΣF=Δp/ΔtImpulse:changeInmomentumIfthemomentumofanobjectchanges,eithermass,velocity,orbothchangeIfmassr

3、emainsthesamethanvelocitychangesaccelerationoccursWhatproducesanacceleration?FORCEGreatertheforceactingontheobjectgreateritschangeinvelocitygreateritschangeinmomentumImpulse:changeinmomentumHowlongtheforceactsisalsoimportant…StalledcarApplyaforceoverabriefamountoftimeproduceachangeinmoment

4、umApplythesameforceoveranextendedperiodoftimeproduceagreaterchangeinthecar’smomentumAforcesuspendedforalongtimeproducesmorechangeinmomentumthandoesthesameforceappliedbrieflyBothforceandtimeareimportantinchangingmomentumImpulse:changeinmomentumIMPULSE(J)=Δp=pf–pi=mvf–mviJ=FavgΔtFavgΔt=mΔvFavg=m

5、Δv/ΔtImpulse(J)=ChangeinmomentumImpulseisalsotheproductoftheaverageforceandthetimeduringwhichtheforceisapplied.VectorquantityUnits:kg*m/sImpulseproblemAlongjumper'sspeedjustbeforelandingis7.8m/s.Whatistheimpulseofherlanding?(mass=68kg)J=ΔpJ=pf-piJ=mvf–mviJ=0-(68kg)(7.8m/s)J=-530kg*m/s*Negatives

6、ignindicatesthatthedirectionoftheimpulseisoppositetoherdirectionofmotionImpulsiveforceBaseballplayerswingsabatandhitstheball,thedurationofthecollisioncanbeasshortas1/1000thofasecondandtheforceaveragesinthethousandsofnewtonsThebriefbutlargeforcethebatexertsontheball=ImpulsiveforceKineticBooksVie

7、wKineticbookssection8.4-Physicsatplay:HittingabaseballBASEBALLPROBLEMTheballarrivesat40m/sandleavesat49m/sintheoppositedirection.Thecontacttimeis5.0×10−4s.Whatistheaverageforceontheball?J=Δp=FavgΔt=mΔvFavgΔt=mΔvFavgΔt=mΔvFavg=mΔv/