資源描述：
《mechanic waves》由會員上傳分享，免費在線閱讀，更多相關內容在教育資源-天天文庫。
1、WaveThedifferentMechanicalwaveswaterwavessoundwavesseismicwaves(地震波)Thesewaveshavecertaincentralfeatures:TheyaregovernedbyNewton’slaws,andtheycanexistonlywithinamaterialmedium,suchaswater,air,androck.1.TransverseWaves(橫波，S波)Thedirectionofoscillationofmediumelementsisperpendicular(垂
2、直)tothedirectionoftravelofthewave.TwotypeofMechanicalwaves2.LongitudinalWaves(縱波，P波)Thedirectionofoscillationofmediumelementsisparallel(平行)tothedirectionofthewave’stravel,themotionissaidtobelongitudinal,andthewaveissaidtobealongitudinalwave.Bothatransversewaveandalongitudinalwavear
3、esaidtobetravelingwavesbecausetheybothtravelfromonepointtoanother,asfromoneendofthestringtotheotherend.sparseanddenseTheTides1Themoon’sgravityactsontheearthThemoon’sgravityisn’tuniformTheearth’soceansarepulledoutofroundT=24hour48minTheTides2TherearetwotidalbulgesintheoceansAstheear
4、throtates,thesebulgesshiftAlmost2highand2lowtidesperdayStrongesttidesnearequatorWeakesttidesnearpolesTheSun’sInfluenceSun’sgravityaffectstidesStrongesttideswhenmoonandsunarealignedWeakesttideswhenmoonandsunareatrightanglesWaterWavesSloshinginvolvesdeepwaterwaves:thewholeliquidmoves
5、backandforthSurfacewavesonlyaffecttheliquid’stopWater’sMotionSurfacewatercirclesasthewavepassesCirclingisstrongestatsurfaceMotionisweakabout1/2wavelengthdeepWaterinaWaveOnlythewavetravels,thewatercirclesCrestsareformedfromlocalwaterQuestion:Youarefloatingmotionlessinaninnertube.You
6、arenearabeachbutfarenoughfromtheshorethatwavesaren'tbreakingontopofyou.YouwilldrifttowardshoreatthespeedofthewavesdriftgraduallytowardshorecircleaswavespassbutnotprogresstowardshoreWavelengthThelongerthewavelengthofasurfacewave,thefasterittravelsthedeeperwatermovesasitpassesthemore
7、energyitcontainsforagivenamplitudeTsunamis（海嘯）areverylongwavelength,verydeep,veryhighenergywavesThepower oftsunamisTsunamisattackJapan 11March,2011How?BreakingWavesSurfacewavesslowdowninshallowwaterWavesbunchasthewatergetsshallowerWavesgettallerasthewatergetsshallowerWavesbreakwhen
8、watercan’tformcrestGradual
