题目内容
有一竖直放置的“T”形架,表面光滑,滑块A、B分别套在水平杆与竖直杆上,A、B用一不可伸长的轻细绳相连,A、B质量相等,且可看做质点,如图所示,开始时细绳水平伸直,A、B静止.由静止释放B后,已知当细绳与竖直方向的夹角为60°时,滑块B沿着竖直杆下滑的速度为v,则连接A、B的绳长为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250043406621008.png)
A.
B.
C.
D. ![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340740571.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250043406621008.png)
A.
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340693508.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340709518.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340724576.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340740571.png)
D
试题分析:由运动的合成与分解可知滑块A和B在绳长方向的速度大小相等,有
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340755845.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340771635.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250043408021007.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340818706.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004340849839.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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