题干

如图所示,一长木板放置在水平地面上,一根轻弹簧右端固定在长木板上,左端连接一个质量为m的小物块,小物块可以在木板上无摩擦滑动.现在用手固定长木板,把小物块向左移动,弹簧的形变量为x1;然后,同时释放小物块和木板,木板在水平地面上滑动,小物块在木板上滑动;经过一段时间后,长木板达到静止状态,小物块在长木板上继续往复运动.长木板静止后,弹簧的最大形变量为x2.已知地面对长木板的滑动摩擦力大小为f.当弹簧的形变量为x时,弹性势能Ep=
1
2
kx2,式中k为弹簧的劲度系数.由上述信息可以判断(   )

A:整个过程中小物块的速度可以达到 km x1

B:整个过程中木板在地面上运动的路程为 k2f (x 12 ﹣x 22

C:长木板静止后,木板所受的静摩擦力的大小不变

D:若将长木板改放在光滑地面上,重复上述操作,则运动过程中物块和木板的速度方向可能相同

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答案(点此获取答案解析)

B

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