题目内容
如图所示,一固定光滑杆与水平方向夹角为
,将一质量为
的小环套在杆上,通过轻绳悬挂一个质量为
的小球,由静止释放后,小环与小球保持相对静止且以相同的加速度
一起下滑,此时绳子与竖直方向夹角为
,则下列说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006554262426.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655333297.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655364362.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655379386.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655395283.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655411339.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006554262426.jpg)
A.杆对小环的作用力大于![]() |
B.![]() ![]() ![]() |
C.![]() ![]() ![]() |
D.若杆不光滑,![]() ![]() |
C
试题分析:以整体为研究对象,分析受力情况,如图:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006558013350.png)
由牛顿第二定律得
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655972951.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656066566.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006560811116.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656097729.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655520415.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250006561281073.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656144957.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656159570.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656206789.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000655520415.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656269486.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656284725.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000656300441.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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