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如图所示,A和B两小车静止在光滑的水平面上,质量分别为m1、m2,A车上有一质量为m0的人,以速度v0向右跳上B车,并与B车相对静止.求:

①人跳离A车后,A车的速度大小和方向;

②人跳上B车后,A、B两车的速度大小之比.

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答案(点此获取答案解析)

解:①设人跳离A车后,A车的速度为vA,研究A车和人组成的系统,

以向右为正方向,由动量守恒定律有 m1vA+m0v0=0,

解得:vA=﹣ m0

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