机械效率,有用功之类的.
机械效率,有用功之类的.
物理人气:141 ℃时间:2019-10-08 21:49:21
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电学中W=Pt力学中W=F(力)s(距离).在力学中,不做功有三种情况:1.用了力,但物体未移动(s=0)2.物体移动了,但没用力(F=0)3.物体即移动,也用了力,但力的方向(力的作用线)与物体移动的方向是垂直的,比如人力运...
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