题目内容
如图所示,A、B为竖直墙壁上等高的两点.AO、BO为长度相等的两根轻绳,CO为一根轻杆。转轴C在AB中点D的正下方,AOB在同一水平面上。∠AOB=90°,∠COD=60°。若在O点处用轻绳悬挂一个质量为m的物体,则平衡后绳AO所受拉力的大小为
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002208193808.jpg)
A.
B.
C.
D.![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000220866632.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002208193808.jpg)
A.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000220819540.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000220835622.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000220850558.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000220866632.png)
D
试题分析:根据等效性原理,AO与BO对O点的拉力可以用与CO与mg共面的力来代替,其方向沿OD方向,根据共点力平衡条件
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000220881846.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002208971065.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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