题目内容
质量为m的小球用长度为L的轻绳系住,在竖直平面内做圆周运动,运动过程中小球受空气阻力作用.已知小球经过最低点时轻绳受的拉力为7mg,经过半周小球恰好能通过最高点,则此过程中小球克服空气阻力做的功为
A.mgL/4 | B.mgL/3 | C.mgL/2 | D.mgL |
C
试题分析:小球在最低点时
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231404237826.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824231405470707.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408242314068891156.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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题目内容
A.mgL/4 | B.mgL/3 | C.mgL/2 | D.mgL |