题目内容
如图所示,AB为竖直转轴,细绳AC和BC的结点C系一质量为m的小球,两绳能承担的最大拉力均为2mg。当AC和BC均拉直时∠ABC=90°,∠ACB=53°,BC=1m。ABC能绕竖直轴AB匀速转动,因而C球在水平面内做匀速圆周运动。当小球的线速度增大时,两绳均会被拉断,则最先被拉断那根绳及另一根绳被拉断时的速度分别为(已知g=10m/s2,sin530=0.8,co530=0.6)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250048155652656.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250048155652656.jpg)
A.AC绳;5m/s | B.BC绳;5m/s | C.AC绳;5.24m/s | D.BC绳;5.24m/s |
B
试题分析:当小球线速度增大,BC和AC均被拉直时,对球:TAsin∠ACB-mg=0…①
TAcos∠ACB+TB=m
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004815581477.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004815597370.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250048156121253.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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