题目内容
如图5-2-8所示,甲、乙两完全一样的小车,质量都为M,乙车内用绳吊一质量为0.5M的小球.当乙车静止时,甲车以速度v与乙车相碰,碰后连为一体.则碰后两车的共同速度为_________________.当小球摆到最高点时,速度为___________________.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209093672412.jpg)
图5-2-8
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241209093672412.jpg)
图5-2-8
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120909398223.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120909413221.gif)
在甲、乙两车碰撞瞬间,甲、乙构成的系统动量守恒,在此瞬间,小球的动量未改变,由完全非弹性碰撞可知:Mv=(M+m)v1,得v1=
.当小球摆到最高点时,三者具有共同的水平速度,设为v2,由甲、乙球在水平方向动量守恒得:Mv=(M+M+0.5M)v2,故v2=
v.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120909398223.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120909413221.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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