判断机械能是否变化的方法.doc

断定机械能是否改变(gǎibiàn)的编制
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机械能包含动能、重力势能和弹性势能。重力做功使重力势能与动能互相转化；弹簧弹力做功使动能和弹性势能互相转化；重力和弹簧弹力同时做功，使动能、弹性势能和重力势能三者间互相转化，机械能总量不变。除此之外其他任何外力对物体做了功，物体所具有的机械能都要改变。断定机械能的改