题目内容
如图所示,范围足够大的匀强电场,场强大小为E,方向竖直向上.一质量为m、带电量+q的小球,在电场中以某一初速度沿电场方向做匀减速直线运动,不计空气阻力,其速度大小为
,物体运动距离为s时速度变为零,则在此过程中( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250046258354222.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004625804389.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250046258354222.png)
A.小球克服电场力做功![]() | B.小球的电势能增加了qEs |
C.小球的机械能增加了qEs | D.小球的动能减少了qEs |
C
试题分析:据题意,带电小球向上做匀减速运动,运动s时速度变为0,由动能定理可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250046258661202.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004625882452.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825004625897659.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250046259131449.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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