题目内容
光滑水平轨道上有三个木块A、B、C,质量分别为
、
,开始时B、C均静止,A以初速度向右运动,A与B相撞后分开,B又与C发生碰撞并粘在一起,此后A与B间的距离保持不变。求B与C碰撞前B的速度大小。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241344514253062.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134451238512.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134451316528.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241344514253062.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134451503617.png)
设AB碰撞后,A的速度为,B与C碰撞前B的速度为,B与V碰撞后粘在一起的速度为,由动量守恒定律得
对A、B木块:
①
对B、C木块:
②
由A与B间的距离保持不变可知
③
联立①②③式,代入数据得
④
对A、B木块:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134451550712.png)
对B、C木块:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134451596748.png)
由A与B间的距离保持不变可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134451628390.png)
联立①②③式,代入数据得
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824134451503617.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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