题目内容
如图所示,在光滑水平面上有一质量为M的小车,小车与绳子的一端相连,绳子的另一端通过不计摩擦的滑轮吊一个质量为m的砝码,砝码离地高h.若把小车从静止开始释放,则当砝码着地时小车的速度为__________,在此过程中,绳子拉力对小车所做的功为____________(此过程中M没有碰到滑轮).
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241204396113678.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241204396113678.jpg)
??
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120439642572.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120439627633.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120439642572.gif)
??小车砝码组成的系统机械能守恒,有:mgh=
(M+m)v2得v=
.对小车,由动能定理:W=Mv2=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120439642572.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120439658225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120439673545.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120439642572.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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