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> 一个小钢球以大小为0.5kg•m/s的动量向下与地板碰撞，然后又以等大的动量向上反弹．则下述说法正确的是（　　） A．若选向上为正方向，则小钢球的动量变化是1kg•m/s B．若选向下为正方向，则小钢球受的冲量是-1N•s C．引起小钢球动量变化的力是重力 D．引起小钢球动量变化的力是地面给小球的弹力

问题：

发布时间：2024-09-11

一个小钢球以大小为0.5kg•m/s的动量向下与地板碰撞，然后又以等大的动量向上反弹．则下述说法正确的是（　　）

A．若选向上为正方向，则小钢球的动量变化是1kg•m/s

B．若选向下为正方向，则小钢球受的冲量是-1N•s

C．引起小钢球动量变化的力是重力

D．引起小钢球动量变化的力是地面给小球的弹力

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