题目内容
如图所示,一个长直轻杆两端分别固定一个小球A和B,两球质量均为m,两球半径忽略不计,杆的长度为
。先将杆AB竖直靠放在竖直墙上,轻轻振动小球B,使小球B在水平面上由静止开始向右滑动,当小球A沿墙下滑距离为
时,下列说法正确的是( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241602336051851.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160233308280.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160233464440.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241602336051851.jpg)
A.小球A和B的速度都为![]() |
B.小球A和B的速度都为![]() |
C.小球A的速度为![]() ![]() |
D.小球A的速度为![]() ![]() |
C
试题分析:A、B两球速度的分解情况如图所示,由题意可知
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160234588496.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160234697768.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241602348841067.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824160235118981.png)
点评:本题难度中等,杆的速度是联系两小球的桥梁,应用机械能守恒定律求解是本题的难点
![](http://thumb2018.1010pic.com/images/loading.gif)
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