英语-三级复习材料unit

Unit ExtremeNarrator:Theaverageskydiverjumpsfromaplaneandfreefalls,reachingspeedsexceeding100perhourinmoments.Followingtheinitialdrop,thediverreachesaconstantspeedofabout perhour,alsoknownas“terminalvelocity”.Terminalvelocityoccurswhenafallingbodyexperienceszeroaccelerationandcan’tgofaster.It'scausedbyair ,or“drag”,whichslowsthebodydownbycreatinganopposingforcetogravity.However,notallskydiversare“average”.Inthehighlycompetitivesportofspeedskydiving,participantsusescientificapproaches—andimagination—togoterminalvelocity.MarkCallandisoneofthesecompetitors.He’samanwhowantsonething:togofaster.MarkCalland,SpeedSkydiver:“It’stheadrenalinerush.Youknowthatyou’regoingfasterthanmostcars.Theonlythingthat’sfasterthanmeispossiblyajetengine.YoutalktopeopleandtheybragabouttheirFerrarisandstufflikethat,youjustturnaroundandsay,‘Well,sorry.IgofasterthanthatandIhaven’tevengotanengineonme.Narrator:Somepeoplecallspeedskydivingthefastestsportintheworldwithoutanengine.Thegoalofthesportissimple.Calland:“JustgetoutoftheplaneandtryandgoasfastaswepossiblycaninfreeNarrator:Becauseofair ,goingfasterwhileskydivingismoredifficultthanitappears—atleastforhumanbeings.Anormalskydiverinfreefallwon’tgomuchfasterthan120perhour.However,thereisonecreatureinnaturethathaslearnedhowtoreachhigherspeeds:theperegrinefalcon.Theperegrineisalsoknownasnature’s“guidedmissile”;whenit’sinanattackdive,it’sthefastestanimalintheworld.Forsometime,nobodyknewjusthowfasttheperegrinefalconwas,untilKenFranklindecidedtofindout.Kentookhisperegrineupto15,000feet,releasedthebird,andjumpedouthimself.WhenKenreachedterminalvelocity,hedroppedaweightedluremadeofmeat.Thefalconsoonmoveditswingsbackinanattackdive.Atinycomputerattachedtothefalconrecordeditsspeedduringtheexperiment.Surprisingly,duringitsfastestdive,thebirdreachedanamazing242 perhour!Backamonghumans,MarkCallandishothatamethodsimilartothatofthefalconwillhelphim.Narrator:Mark’scometotheworldspeedskydivingchampionshipatadropzoneinthenorthofEngland.He’soneofthefastestskydiversintheworldandtheholderoftheBritishrecord.HismaincompetitionisgoingtocomefromMarcoWiederkehr.He’sthenationalchampionofLiechtensteinandaworthychallengerforMark.MarcoWiederkehr,SpeedSkydiver:“Well,let’sgoNarrator:Techniquesusedbycompetitorsvary,butthesecretseemstoberelativelyplicated:justjumpoutofanairplane,diveatinhumanspeedstowardground—sometimesheadfirst—andremain yCalland:“Yeah,youhavegottobetotally...justnothinginyourmindatall.You’vejustgottoreallyfeel...You’vegottofeelhowyourbodyisflyingandhowit’sreacting.”Narrator:AsMarkstepsintospace,hemoveshisheadbackwardandadjustshisbody.Byheadfirst—liketheperegrinefalcon—theeffectsofair arereduced.Calland:“Reasonablyfastformyfirstjump.”Narrator:Inthecompetition,participantsusetheaveragespeedoftheirthreebestjumps.Speedsaremeasuredbyspeedometersattachedtotheirharnesses.Mark’sfirstjumpis302 perhour.That’sfast,butnowit’sMarco’sturn.Hethrowshimselffromtheplane,knowingthathemustbeatMark’sfirstdivespeed.Aftertenseconds,Marcoreaches100 perhour,by16,hehits200!Twelvesecondslater,he’sdoneit!He’sreachedanewworldrecord—312,or502kilometers,perhour!Calland:“Marco’sgotNarrator:It’snowcleartoMarkthathehassomerealcompetition,buthe’sconfidentthatMarcocan’tmaintainthathighspeedoneveryjump.Mark’sfocusingongoingfastconsistently.Besides,he’sgotsomethingthatmayallowhimtogofaster...Speedskydiversuseeverythingtheycantoimprovetheirspeeds,includingspecialhelmetsandclothing.Usingawindtunneltotestthewind ofhisbody,Markhasdevelopedaspecialsuitwithpantsthatfillwithair.Calland:“Thesepantsareactuallybigairscoops.Um,thebottomhalfofthepantsactuallyinflatesanditgivesyoutheshuttlecockeffect.”Narrator:Whenusingthepants,Mark’sbodyisalmostlikeabadmintonshuttlecock.Hisstronglybuiltupperbodyisliketherubbertipofashuttlecock.Hisair-filledpantsarelikethefeathersattheotherend.ThepantsincreaseMark’sdrag,buttheygivehimmuchmorecontrol.Wearingthemmakesiteasierforhimtoremainrelaxedwhilehe’shangingupsidedownandflyingtowardstheearth.Gravitydoestherest.Marcodoesn’thaveinflatablepants,justasmoothrubbersuitwhichistight-fittingtokeepairataminimum.Unfortunay,thisjumpisadisappointmentandhe’sunabletocontrolhisfall.Asheworkstokeephimselfpointedstraightdownduringthejump,helosesvaluableperhour.Calland:“Marco,howwasyourWiederkehr:“Gotintotheclouds,thenabitwobbly.Speedisnotsohigh,theumspeed.”Narrator:Onhisnextandfinaljump,Mark,however,doesn’twobble.TheskydivegoesbeautifullyandMarkisabletomaintaincontrolthroughoutit.Hiswind-filledclothinggiveshimtheadvantageheneedstoachievethreeverygoodjumpsandhisaveragespeedisthehighestofallthecompetitors.Announcer:“Men’sEvent;firstplace...MarkNarrator:Mark’sscientificapproachtoskydivinghaspaidoff.Fortodayatleast,it’smadehimthebestspeedskydiverintheworld!HOMEAudioAHistoryofAlthoughthereissomeevidencethatparachutesappearedinChinainthe1100s,theearliestrecordedexampleofskydivingisslightlylater.LeonardodaVincihasbeenattributedwithdesigningthefirstdraftsofaparachute-likemechanism.Inabout1495,hedesignedsix-meter-longtriangularparachutewhichwasheldtogetherbyflexiblewoodensticks.Sinceairplanesorothermethodsofflyinghadnotbeeninventedyet,thetestingofdaVinci’sparachutewaslimitedtojumpsfromtrees,towersandcliffs.InJuly2000,BritishskydiverAdrianNicholstesteddaVinci’sdesign.Nicholsstatedthat,althoughthereweresafetyissuesduetotheparachute’sweight,theflightwasdefiniysmootherthanamodernparachute.TheFirstModernThefirstparachutethatwassimilartothoseusedtodaywasinventedbyaFrenannamedAndré-JacquesGarnerin.Asasoldier,GarnerinwastakenprisonerinHungarywherehebeganexperimentingwithparachutesaspartofhisplantoescape.In1797,severalyearsafterbeingfreed,heconstructedthefirstmodernparachute.Hisdesignconsistedofaratherinflexibleframeworkcoveredwithwhiteclothandlookedalotlikealargeumbrella.Hemadeasuccessful975-meterjumpfromahot-airballoonin1797,andin1799hiswife,JeanneGenevieve,becamethefirstwomantouseaparachutetomakeasimilarjump.TheBirthofParachutingmovedtoanotherlevelaftertheinventionoftheairplaneintheearly1900s.DuringWorldWarI,parachutistsbecameanimportantpartofthefightingforces.Thisbroughtattentiontoparachutingandafterthewar,parachutistsbegantoappearinpublicperformances.However,itwasmanyyearsbeforetheterm“skydiving”wascreated,andskydivingwasn’tactuallyacceptedasasportbytheWorldAirSportsFederation(WASF)untilthemid-1950s.SkydivingAsthepopularityofthesportgrew,theWASFdevelopedrulesforcompetitionsandteamsandindividualsbegantocompeteforprizesinawidevarietyofareas,includingthefollowing:LargestFreefallFormation(thelargestgroupjumatthesameLargestFreefallFormationHead-Down(thelargestgroupjumheadfirstatthesametime)LargestCanopyFormation(thelargestgrouptouchingeachother’sopenparachutes)Accuracy(thecompetitorwhoachievesthemostaccuraterepeatedlandingsonathree-centimeter-widetarget)

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