题目内容
如图,可视为质点的小球A、B用不可伸长的细软轻线连接,跨过固定在地面上、半径为R的光滑圆柱,A的质量为B的两倍。当B位于地面时,A恰与圆柱轴心等高。将A由静止释放,B上升的最大高度是
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002395087634.png)
A. 2R B. 5R/3 C. 4R/3 D. 2R/3
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002395087634.png)
A. 2R B. 5R/3 C. 4R/3 D. 2R/3
C
试题分析:设A落地时的速度为V, A下落时, A、B组成的系统机械能守恒,
则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250002395231154.png)
得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000239539715.png)
此时B恰好运动到与圆心等高处,速度也为V,接下来B球做竖直上抛运动,
再上升的高度
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000239679339.png)
由
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000239695816.png)
可得
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000239711597.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000239742772.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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