Unit8 General ScienceWork and Power

Unit8GeneralScience,WorkandPower,Learningaims:,1.Masterthekeywordsandexpressions:power,work,plus,minus,multipliedby,dividedby,equals,hedirectionof2.Canreadthetextsmoothly.3.CanreadthecalculationsinEnglish.,Task1Newwordsandexpressions,Translatethefollowingwordsandexpressions.1.power_2.work_3.plus_4.minus_5.multipliedby_6.dividedby_7.equals_8.workdone_9.preventsb.fromdoingsth._10.inthedirectionof_,功率,功,加,减，减去,乘以,除以,等于,功,所做的功,阻止某人做某事,沿着方向,Task2:Fastreading,Scanthetextquicklyandfindouttheanswersofthefollowingquestions.1.Whatisthedefinitionof“work”?Workis2.Howdoyoucalculatetheamountofworkdone?,donewhenaforcecausesanobjecttomoveorpreventsitfrommoving.,(Itcanbecalculatedusingthefollowingequation:)Workdone=forcedistancemovedinthedirectionoftheforce,3.WhatisthedefinitionofIjoule?1jouleisthat4.Whatisthedefinitionof“power”?Poweris5.Whatisthedefinitionof1“watt”?,aforceof1Ncausesanobjecttomove1meter.,ameasureofhowrapidlyworkisbeingdone.,Ifapersonoramachineisdoing1Jofworkeachsecond,thepowerratingis1W.,Task3.Carefulreading,Readthetextagain,andthentellwhetherthefollowingstatementsaretrue(T)orfalse(F).()1.Toscientistsworkmeansjob.()2.Workisdonewhenaforcecausesanobjecttomoveorpreventsitfrommoving.()3.Workdoneequalstoforcedividedbydistancemovedinthedirectionoftheforce.()4.Ifaforceof2Ncausesanobjecttomove2meters,then4Jofworkhasbeendone.()5.Powerisameasureofhowmuchworkisbeingdone.,T,T,F,F,F,()6.Powerequalstoworkdonemultipliedbytimetaken.()7.Powerismeasuredinjoule.()8.Forcecanbemeasuredinnewton.()9.Thecalculation80N-30N=50Ncanbeexplainedinword:80newtonsplus30newtonsequals50newtons.()10.Ifapersonisdoing1Jofworkeachsecond,thepowerratingis1W.,T,F,F,F,T,Task4:Carefulreading,Readthetextagain,thenreadthefollowingcalculationsinEnglish.Workdone=2000N2m=4000JWorkdone=30N40m=1200JPower=workdonetimetakenPower=4000J0.5s=8000w,Task5.Excises:Workoutthefollowingquestionsbygivingtheequationandtheresult.,Example:Question:WangPinghasfifteenpenpilsandhegivesthreeofthemtoLiYang.Howmanypencilsleft?Answer:15-3=12Therearetwelvepencilsleft.,1.Thestudentsinourschoolplantedonethousandtreeslastyears,andtheyplantedtwothousandtreesthisyear.Howmanytreesdidtheyplantthesetwoyears?_Theyplanted2.MumgaveTomtwentydollarsyesterdayandhespenttwelveofthembuyingthebookstoday.Howmuchmoneyisleftnow?_Hehasleft3.Lisahasearnedeighteendollarsbydeliveringthenewpaper,whileJennyhasearnedtwiceasmuchasLisa.HowmuchmoneyhasJennyearned?_Jennyhas,1000=2000=3000,threethousandtrees.,20-12=8,eightdollars,earnedthirty-sixdollars,182=36,4.Thereareonehundredandtwentystudentsinourteam.Theteacherdividesusintofourgroupsinaverage(平均).Howmanystudentsarethereinonegroup?_Therearestudentsinonegroup.5.Therearetenhens,threedogs,twocatsandfivebirdsinmyfamily.Howmanyanimalsarethereinmyfamilyalltogether?_Thereareanimalsinyourfamily.,1204=30,thirty,10+3+2+5=20,twenty,6.Youborrowedtenstorybooksfromthelibraryyesterdayandreturnedfiveofthemtothelibrarytoday.Howmanybooksarelefttoyou?_storybooksarelefttome.7.Ihavefiftycopiesofnewspapernow;Iwanttogivehalfofthemtomyfriend.Howmanycopieswillbelefttome?_copieswillbelefttoyou.,10-5=5,Five,502=25,Twenty-five,HomeWork:Group1:Readthetext”Work