上海新世纪英语高二全部课文及重点词组上海新世纪英语高二全部课文及重点词组somepeopleestimateyuan’sactualfortunemightmakehimoneoftherichestpeopleinchina.buthedoesn’tknowforsurehimself,forheseemstocarefornothingmorethanhisresearch.inspiteofhisbusyresearchwork,yuanlongpinhasmanagedtokeepsomehobbiesinhissparetime,includingreadingbooksandlisteningtomusic.heenjoysdailymotorcyclingandsometimesplayingtheviolin.28.newton’sthreeimportantlawsthingsthatmoveobeycertainlaws.threeimportantlawsofmotionwereestablishedbyisaacnewton(1642～1727)(英国物理学家、天文学家和数学家，被公认为有史以来最伟大和影响最深远的科学家).newtonⅰ:inertia(惯性定律)newton’sfirstlawofmotionseemssimple:objectsatresttendtoremainatrest,whilemovingonescontinuetomoveatauniformspeedinastraightline---unlessacteduponbyanoutsideforce.thisresistance(阻力)tochangeiscalledinertia,anditexplainsalotofeverydayexperiencednomatterwhereyouhappentolive.oneisthatwhenthecarorairplaneyou’reinbeginstomove,yourbodyispushedbackagainsttheseat.thatis,ittendstoremainatrestdespitetheforward-movingforceofthevehicletransferredtoyouthroughtheseat.anotheraspectofthislawshowsthatthenormalcoursesforfreelymovingobjectsisastraightline.thatexplainswhy,whenyouwhirl(迅速旋转)somethingaroundyourhead---suchasaballonastring---andthenletitgo,theballfliesstraight.itneitherkeepscirclingyourheadnordoesitmoveoffinasweeping(做大幅度弧线形运动的)curve(曲线).newtonⅱ:f=manewton’ssecondlawrelatestheamountofforceneededtomoveanobjecttotheobject’smassandtitsacceleration(加速度).pushachildinaswing,orrideaplanetaroundthesun,andyou’reusingnewton’ssecondlawofmotion,whichstatesthatwheneveryouwanttochangethespeedordirectionofsomething,youhavetoapplyanappropriateforce.thebiggerthemassorthelargertheintendedacceleration,thegreaterthenecessaryforce.thislaw’sformulaallowsengineerstocalculatewhat’srequiredtolaunchajetfighter(喷气式战斗机)fromanaircraftcarrier(航空母舰),orhowstrongaseatbeltmustbetorestrain(抑制，控制),say,a160-poundpersonwhenhiscarstopssuddenlywhiletravellingat60mph.newtonⅲ:equalandopposite(作用力与反作用力)allobjects,movingoratrest,obeynewton’sthirdlawofmotion,whichholdsthatin