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Unit8GeneralScienceWorkandPower功和功率*功表示力和受力物体在力的作用方向上发生的位移的乘积。*功率表示力做功的快慢程度。TWW=F*SP=FastreadingReadthetextquicklyandanswerthefollowingquestions.1.Whatisthedefinitionof“work”?2.Howdoyoucalculatetheamountofworkdone?3.Whatisthedefinitionof1joule?4.Whatisthedefinitionof“power”?5.Whatisthedefinitionof1watt?Workisdonewhenaforcecausesanobjecttomoveorpreventsitfrommoving.thedefinitionof“work”:Equation:W=F*SWorkdone=forceXdistancemovedinthedirectionoftheforceWorkdoneequalsforcetimesdistancemovedinthedirectionoftheforce.ExampleAnathleteappliesaforceof2000newtonstomoveuptheweightstotheheightof2meters.Howmuchworkhastheathletedone?2000N2mWorkdone=2000NX2m=4000J1jouleIfaforceof1Ncausesanobjecttomove1meter,then1Jofworkhasbeendone.1N1mThedefinitionof“power”•Powerisameasureofhowrapidlyworkisbeingdone.Power=timetakenworkdone1wattIfapersonoramachineisdoing1Jofworkeachsecond,thepowerratingis1W.ExampleGoonlookingattheathlete,iftheworktakestheathlete0.5secondtolifttheweightsabovehishead,whatisthepoweroftheathlete?Power=sJ5.04000=8000Wor8KwSumup•Work;workdone;1Joule;power;1Watt.•Workdone=2000NX2m=4000J•Power=4000J÷0.5s=8000wor8kwHomework•Thelawnmowermoveneeds80newtons,itsenginecanapply50newtons.Aladypushedthelawnmoweralongastraightslinefor40meters.Howmuchworkhastheladydone?