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动量定理

> 质量为m的钢球自高处落下，以速度v 1碰地，竖直向上弹回，碰撞时间极短，离地的速度为v 2，在碰撞过程中，地面对钢球的冲量的方向和大小为 [ ] A．向下，m（v 1-v 2） B．向下，m（v 1+v 2） C．向上，m（v 1-v 2） D．向上，m（v 1+v 2）

问题：

发布时间：2024-09-07

质量为m的钢球自高处落下，以速度v ₁碰地，竖直向上弹回，碰撞时间极短，离地的速度为v ₂，在碰撞过程中，地面对钢球的冲量的方向和大小为
[ ]
A．向下，m（v ₁-v ₂）
B．向下，m（v ₁+v ₂）
C．向上，m（v ₁-v ₂）
D．向上，m（v ₁+v ₂）

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