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冲量

> 质量为 m的钢球自高处落下，以速率 v 1碰地，竖直向上弹回，碰撞时间极短，离地的速率为 v 2．在碰撞过程中，钢球受到的冲量的方向和大小为 A．向下，m（v1－v2） B．向下，m（v1＋v2） C．向上，m（v1－v2） D．向上，m（v1＋v2）

问题：

发布时间：2020-03-13

质量为 m的钢球自高处落下，以速率 v ₁碰地，竖直向上弹回，碰撞时间极短，离地的速率为 v ₂．在碰撞过程中，钢球受到的冲量的方向和大小为

A．向下，m（v₁－v₂） B．向下，m（v₁＋v₂）

C．向上，m（v₁－v₂） D．向上，m（v₁＋v₂）

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