题目内容
重为G的两个完全相同的小球,与水平面的动摩擦因数均为
。竖直向上的较小的力F作用在连接两球轻绳的中点,绳间的夹角α = 60°,如图所示。缓慢增大F,到两球刚要运动的过程中,下列说法正确的是
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242310243863941.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231023310301.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242310243863941.png)
A.两根绳子的拉力逐渐减小 |
B.地面对球的支持力变大 |
C.球刚要开始运动时,地面对球没有支持力 |
D.球刚要开始运动时,球受到的摩擦力最大 |
D
试题分析:设两绳的拉力均为T,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231025650765.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231026976738.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231028302581.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231029674297.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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