··4cco周讓Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL死海不死為什么淹寫(xiě)不死他們?是神在保護(hù)他仉嗎浮力的來(lái)源?答案:水第一課時(shí)Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL書(shū)一活動(dòng)·空瓶壓入水中,手會(huì)明顯感受到向上的壓力·將手松開(kāi)后,瓶子將迅速上升,然后浮出水面·結(jié)論:水中會(huì)上浮的物體受到向上的浮力。Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL漂浮在水面的木塊,受到的浮力>重力???物體漂浮時(shí)受到的浮力=重力在水中會(huì)上浮的物體受到向上的浮力。那么,在水中會(huì)下沉的物體是否也受到水的浮力呢?Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL彈簧測(cè)力器0彈簧2指針刻度盤(pán)秤鉤Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL讀一讀02二01234514牛2.6牛3.6牛Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL書(shū)【活動(dòng)】P111、將物體掛在彈簧測(cè)力計(jì)下,記下彈簧測(cè)力計(jì)的讀數(shù)F12、再將物體浸入水中,記下彈簧測(cè)力計(jì)的讀數(shù)F23、比較彈簧測(cè)力計(jì)的讀數(shù)變化,你能得到什么結(jié)論?實(shí)驗(yàn)次數(shù)空氣中讀數(shù)F1(牛)水里讀數(shù)F2(牛)Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL這個(gè)實(shí)驗(yàn)說(shuō)明了什么2?在水中會(huì)下沉的物體也會(huì)受到水的浮力Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL上述實(shí)驗(yàn)?zāi)艿玫揭环N用彈簧秤測(cè)浮力的方法?稱量法測(cè)浮力大小:彈黌秤兩次示數(shù)差浮=1條件:物體能沉入水中Valadononry.chAsposeslidesforNET4odientPEvaluationonly.CreatedwithAsposeSlidesforNET4.0dientProfilo71Copyright2019-2019AsposePtyL負(fù)式生習(xí)在空氣中用彈簧秤稱一物體重為15牛,把它浸沒(méi)在水中稱得重5牛,則它受到得浮力為10N牛;把它浸入一半時(shí)稱得重為10牛這時(shí)物體受到水的浮力為_(kāi)5N牛.Valadononry.chAsposeslidesforNET4odientPEv