题目内容
如图所示,质量为M的平板车的长度为L,左端放一质量为m的小物块,今使小物块与小车一起以共同速度v0沿光滑水平面向右运动,小车将与竖直墙发生弹性碰撞,而小物块最终又恰与小车相对静止于小车的最右端,求小物块与小车上表面间的动摩擦因数。![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241201046272845.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241201046272845.jpg)
当m<M时,
=
;当m>M时,
=
。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104643204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104721681.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104643204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104783660.gif)
(1)当m<M时,小车与竖直墙做弹性碰撞后小车和物体与小物体分别以速率v0向左向右运动,最后共同速度为v
Mv0-mv0=(M+m)v?
mgL=
(M+m)v02-
(M+m)v2?
解得:
=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104721681.gif)
(2)当m>M时, 小车与竖直墙第一次弹性碰撞后分别以v0向左、向右运动.
p物>p车. 相对静止时速度为v,方向向右, 发生第二次弹性碰撞, 多次往复运动, 最终小车与物块将静止, 则
mgL=
(m+M)v02
=![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104783660.gif)
Mv0-mv0=(M+m)v?
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104643204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104814225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104814225.gif)
解得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104643204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104721681.gif)
(2)当m>M时, 小车与竖直墙第一次弹性碰撞后分别以v0向左、向右运动.
p物>p车. 相对静止时速度为v,方向向右, 发生第二次弹性碰撞, 多次往复运动, 最终小车与物块将静止, 则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104643204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104814225.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104643204.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824120104783660.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目