题目内容
如图5所示,质量为M的木板,上表面水平,放在水平桌面上,木板上面有一质量为m的物块,物块与木板及木板与桌面间的动摩擦因数均为
,若要以水平外力F将木板抽出,则力F的大小至少为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142238273847.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114223718204.gif)
A.![]() | B.![]() |
C.![]() | D.![]() |
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142238273847.gif)
D
将木板抽出的过程中,物块与木板间的摩擦力为滑动摩擦力,m的加速度大小为
,要抽出木板,必须使木板的加速度大于物块的加速度,即
,对木板受力分析如图12,根据牛顿第二定律,得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142238742406.gif)
选项D正确
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142239051065.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114223843406.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824114223859498.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142238742406.gif)
选项D正确
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241142239051065.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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