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1、Unit2Sailingtheoceans-Textbook课件Inpairsdiscussthesequestions:1Whatisanavigator?Anavigatorexploresnewroutesacrossthesea.2Whatisthedifferencebetweenanavigatorandanexplorer?Anavigatorexploresthesea;anexplorerdiscoversnewplacesonland.WarmingUp3Lookatthesefamouspeople.Aretheyn
2、avigatorsorexplorers?Whatdoyouknowaboutthem?NavigatorseanauticalinstrumentsfindnewislandsorcontinentsNavigatorissomeonewhofindsthepositionandplotsthecourseofaship,anaircraft,acar,etc,usingmapsandinstruments.Explorerlanduseofcompassandlandmarksfindnewplaceswithinanalreadyi
3、dentifiedislandorcontinentExplorerissomeonewhotravelsintoorthroughaplaceinordertolearnaboutit.Veryoftennavigatorsarealsoexplorers.Lookatthepictures.Thenanswerthequestions.1Howdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented?Keptclosetothesh
4、ore,usednaturesuchasthesun,wind,birds,tide,etc,tohelpthem,andusedsomeoftheinstrumentsincludingacompass,astrolabe,etc.Pre-reading2Whichdoyouthinkwaseasiertoworkout:latitudeorlongitude?Latitude,becauseitwasusedtomeasurehowfaryouhadtravelledfromlandonastraightline.Itwasdisco
5、veredalongtimebeforelongitude.3Canyouidentifytheseearlynavigationalinstrumentsseamenusedandexplainhowtheyareused?1_________________________2_________3_________4________________________4Whichonesdoyouthinkarestillusedtoday?Seachartsarestillusedtoday.compass(inancientChina)
6、astrolabesextantsea/nautical/marinechartReadthepassageandanswerthefollowingquestions.1Whatistheuseofabearingcircle,astrolabe,quadrantorsextant?()Whatistheuseofacompass?()AtosetthecourseoftheshipBtomeasurethepositionoftheshipCtomeasurethespeedoftheshipDtotellthetimeCompreh
7、ending1BA2Whyarespeedandtimeimportantinworkingoutthelongitudeofaship?Speedandtimeareimportantinfindingoutthelongitudeofashipbecausetheearthmovesfifteendegreeswestwardseveryhour.Ifyouknowyourdirection,speedandtime,youcanworkouttheapproximatelongitudeorchangeinyourpositioni
8、nrelationtothestars.3Whyisthepositionofthesunandvariousstarsusefulforworkingoutlatitude?Theposit
