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ID:48802466
大小:1.56 MB
页数:39页
时间:2020-01-26
《Warmingup、Pre-reading、Reading、Comprehending (15).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、Unit2SailingtheoceansReading选修九Pre-readingLookatthepicturesonpage11.Thenanswerthequestions.compassAstrolabe(星盘)Sextant(六分仪)sea/nauticalchart1Howdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented?Keptclosetotheshore,usednaturesuchasthes
2、un,wind,birds,tide,etc,tohelpthem,andusedsomeoftheinstrumentsincludingacompass,astrolabe,etc.2Whichdoyouthinkwaseasiertoworkout:latitudeorlongitude?Latitude,becauseitwasusedtomeasurehowfaryouhadtravelledfromlandonastraightline.Itwasdiscoveredalongtimebeforelongitud
3、e.3Canyouidentifytheseearlynavigationalinstrumentsseamenusedandexplainhowtheyareused?1_________________________2_________3_________4________________________compass(inancientChina)astrolabesextantsea/nautical/marinechart4Whichonesdoyouthinkarestillusedtoday?Seachart
4、sarestillusedtoday.aquadrant(四分仪)aspecialtoolfortellingthepositionoftheshipinrelationtothesunandvariousstarsanastrolabemeasurehowhighstarswereabovethehorizonearlynavigationalinstrumentsanupdatednavigationalinstrumenttomeasuretheanglebetweentwofixedpointsoutsidethes
5、hipsextantabearingcircle方位圆thefirstinstrumenttomeasurethesun’spositionandthesun’sshadowSAILINGTHEOCEANSReadingNowreadaboutwhatnavigationwaslikebeforemoderninstrumentswereused.1Whatistheuseofabearingcircle,astrolabe,quadrantorsextant?()Whatistheuseofacompass?()Atose
6、tthecourseoftheshipBtomeasurethepositionoftheshipCtomeasurethespeedoftheshipDtotellthetimeBAComprehending1Readthepassageandanswerthefollowingquestions.Speedandtimeareimportantinfindingoutthelongitudeofashipbecausetheearthmovesfifteendegreeswestwardseveryhour.Ifyouk
7、nowyourdirection,speedandtime,youcanworkouttheapproximatelongitudeorchangeinyourpositioninrelationtothestars.Whyarespeedandtimeimportantinworkingoutthelongitudeofaship?Thepositionofthesunandstarsareusefulforworkingoutlatitudebecausetheyarefixedpointsintheskyandthei
8、rmovementsinrelationtotheeartharealreadyknown.Sotheycanbeusedtomeasureaship'sposition.3Whyisthepositionofthesunandvariousstarsusefulforworkingout
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