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Howdoesthekineticenergywithwhichtheverticallyprojectedspherehitsthefloorcomparewiththatforthehorizontallyprojectedsphere?不是后者多了个水平速度么,为啥答案说是Itisthesame呢?

题目详情
How does the kinetic energy with which the vertically projected sphere hits the floor compare with that for the horizontally projected sphere?
不是后者多了个水平速度么,为啥答案说是It is the same呢?
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答案和解析
小球初始V方向不同,但数值相同,所以初始动能相同.在触地的瞬间,小球的动能等于初始动能加上重力势能转变的动能,这也相同,所以,在触地瞬间两小球的动能值是相同的呀,能量守恒啊.只是两球速度方向不同罢了.动能不是矢量,不管方向的呀.