题目内容
如图所示,轻杆长为3L=30cm,在杆的A、B两端分别固定质量均为m=
的小球A和B,杆上距球A为L处的点O装在光滑的水平转动轴上,杆和球在竖直面内转动,已知球B运动到最高点时,球B对杆恰好无作用力.则此时B的线速度
;当B球以相同的线速度转到最低点时,A球对杆的作用力
,杆对B球的作用力
。(g取10m/s2)![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326430113298.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132642870500.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132642902284.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132642933393.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132642964391.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241326430113298.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643026336.png)
球B对杆恰好无作用力,重力完全提供向心力,则有:
,
;B与A的角速度相等,则
,A球做圆周运动有:
,
,杆对B球有:
,![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643260590.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643058761.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643089829.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643136582.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643167861.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643198631.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643214919.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824132643260590.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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