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> 一位质量为m的运动员从下蹲状态向上起跳，经△t时间，身体伸直并刚好离开地面，速度为v。在此过程中 [ ] A．地面对他的冲量为mv+ mg△t，地面对他做的功为mv 2/2 B．地面对他的冲量为mv+mg△t，地面对他做的功为零 C．地面对他的冲量为mv，地面对他做的功为mv 2/2 D．地面对他的冲量为mv-mg△t，地面对他做的功为零

问题：

发布时间：2024-09-09

一位质量为m的运动员从下蹲状态向上起跳，经△t时间，身体伸直并刚好离开地面，速度为v。在此过程中
[ ]
A．地面对他的冲量为mv+ mg△t，地面对他做的功为mv ²/2
B．地面对他的冲量为mv+mg△t，地面对他做的功为零
C．地面对他的冲量为mv，地面对他做的功为mv ²/2
D．地面对他的冲量为mv-mg△t，地面对他做的功为零

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