题目内容
特种兵过山谷的一种方法可化简为如右图所示的模型:将一根长为2d、不可伸长的细绳的两端固定在相距为d的A、B两等高处,悬绳上有小滑轮P,战士们相互配合,可沿着细绳滑到对面。开始时,战士甲拉住滑轮,质量为m的战士乙吊在滑轮上,处于静止状态,AP竖直,则此时甲对滑轮的水平拉力为_________mg;若甲将滑轮由静止释放,则乙在滑动中速度的最大值为_________。(不计滑轮与绳的质量,不计滑轮的大小及摩擦)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250003253103630.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250003253103630.jpg)
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![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325325784.png)
试题分析:设开始位置绳子的拉力为T,PB与竖直线的夹角为α,则对滑轮,水平方向
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325341585.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325356752.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325372908.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325388577.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325403566.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325419585.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000325325784.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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