题目内容
如图所示,光滑曲面上方有一固定的带电量为
的点电荷,现有一带电量为
的金属小球(可视为质点),在
点以初速度
射入后始终沿着曲面运动,小球与面相互绝缘,则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250008157662734.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000815704361.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000815720330.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000815735295.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000815751321.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250008157662734.jpg)
A.小球从![]() |
B.小球从![]() |
C.小球在C点时受到![]() |
D.小球在曲面上运动过程中,机械能始终守恒 |
B
试题分析:据题意,小球从A点开始运动过程中,受到重力G、支持力N和电场力F,小球从A运动到B的过程中,由动能定理得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000815844953.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250008158601067.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000815907923.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825000815922968.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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