题目内容
如图所示,质量为m、顶角为α的直角劈和质量为M的正方体放在两竖直墙和水平面间,处于静止状态. 若不计一切摩擦,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007041942406.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007041942406.jpg)
A.正方体对水平面的弹力大小为(M+m)g |
B.墙面对正方体的弹力大小mgtanα |
C.正方体对直角劈的弹力大小为mgcosα |
D.墙面对直角劈的弹力大小mgsinα |
A
试题分析:正方体和直角劈作为一个整体,竖直方向有地面支持力
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704225357.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704240687.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704240319.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704272365.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704272820.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704287440.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704272820.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704381778.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704396732.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000704459857.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250007044746284.jpg)
![](http://thumb2018.1010pic.com/images/loading.gif)
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