题干

如图所示,质量为m的物体放在水平放置的钢板C上,物体与钢板的动摩擦因数为μ,由于光滑导槽AB的控制,该物体只能沿水平导槽运动,现使钢板以速度v向右运动,同时用力F沿导槽方向拉动物体使其以速度v1沿槽运动,其中v1 与v大小相等,则F的大小为(    )

A:2μmg

B:μmg

C:μmg/

D:不能确定

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C

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