题目内容
如图所示,光滑斜面静止于粗糙水平面上,斜面倾角θ=30°,质量为m的小球被轻质细绳系住斜吊着静止于斜面上,悬线与竖直方向夹角α=30°,则下列说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242220569333161.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242220569333161.png)
A.悬线对小球拉力是![]() |
B.地面对斜面的摩擦力是![]() |
C.将斜面缓慢向右移动少许,悬线对小球拉力减小 |
D.将斜面缓慢向右移动少许,小球对斜面的压力减小 |
AD
试题分析:对小球受重力mg斜面的支持力N和细绳的拉力T作用,如解图甲所示,根据共点力平衡条件可知,N和T的合力F与mg等大反向,又由图中几何关系可知,N和T与竖直方向的夹角均为30°,因此有:mg=
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222100100435.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222057698630.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222102877663.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242221041725866.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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