题目内容
如图所示,质量为M的斜劈状物A放置在水平面上,从它的光滑斜面顶点,由静止开始释放质量为m的物体B,在B沿A的斜面下滑的过程中,A一直保持静止,A的倾角为
,则在B下滑过程中,地面所受压力为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241231149011452.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123114885287.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241231149011452.png)
A.![]() | B.![]() |
C.![]() | D.![]() |
D
物体B受重力和支持力,支持力
,根据牛顿第三定律可知,物体B对A的压力大小也为
,物体A受重力,支持力,压力,地面对它的摩擦力而平衡,根据平衡,可列出竖直方向的平衡方程为![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123115244981.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123115182866.png)
故选D
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123115197744.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123115213595.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123115244981.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824123115182866.png)
故选D
![](http://thumb2018.1010pic.com/images/loading.gif)
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