题目内容
如图,OP为粗糙的水平杆,OQ为光滑的竖直杆,质量相同的两个小环a、b,通过细线连接套在杆上,a环在A位置时平衡.当a环移到
位置时也恰好平衡,在A位置水平杆受到的压力为
,细线的拉力为
,在
位置水平杆受到的压力为
,细线的拉力为
,则下述结论正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241450292153467.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145028778332.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145028840428.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145028950333.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145028996328.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145029059452.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145029137352.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241450292153467.jpg)
A.![]() ![]() | B.![]() ![]() |
C.![]() ![]() | D.![]() ![]() |
B
试题分析:以小球B为研究对象,受到重力、绳子的拉力和杆水平向左的支持力,设绳子与竖直方向夹角为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824145030541834.png)
点评:在应用整体隔离法求解问题时注意研究对象的选择,分析外力时要以整体为研究对象,一切内力都不分析,当求解内力时要用隔离法分析部分受力情况
![](http://thumb2018.1010pic.com/images/loading.gif)
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