语文版中职英语（拓展模块）Unit8《GeneralScience》ppt课件.ppt

《语文版中职英语（拓展模块）Unit8《GeneralScience》ppt课件.ppt》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、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。W=F*SP=FastreadingReadthetextquicklyandanswerthefollowingquestions.1.Whatisthedefinitionof“work”?2.Howdoyoucalculatetheamountofworkdone?3.Whatisthedefinitionof1joule?4.Whatisthedefinitionof“power”?5.Whatisthedefin

2、itionof1watt?Workisdonewhenaforcecausesanobjecttomoveorpreventsitfrommoving.thedefinitionof“work”:Equation:W=F*SWorkdone=forceXdistancemovedinthedirectionoftheforceWorkdoneequalsforcetimesdistancemovedinthedirectionoftheforce.ExampleAnathleteappliesaforceof2000newtonstomoveuptheweightstot

3、heheightof2meters.Howmuchworkhastheathletedone?2000N2mWorkdone=2000NX2m=4000J1jouleIfaforceof1Ncausesanobjecttomove1meter,then1Jofworkhasbeendone.1N1mThedefinitionof“power”Powerisameasureofhowrapidlyworkisbeingdone.Power=1wattIfapersonoramachineisdoing1Jofworkeachsecond,thepowerratingis1W

4、.ExampleGoonlookingattheathlete,iftheworktakestheathlete0.5secondtolifttheweightsabovehishead,whatisthepoweroftheathlete?Power==8000Wor8KwSumupWork;workdone;1Joule;power;1Watt.Workdone=2000NX2m=4000JPower=4000J÷0.5s=8000wor8kwHomeworkThelawnmowermoveneeds80newtons,itsenginecanapply50newto

5、ns.Aladypushedthelawnmoweralongastraightslinefor40meters.Howmuchworkhastheladydone?goodbye