题目内容
如图两块平行金属板M、N竖直放置,两板间电势差U=1.5×103 V。现将质量m=1×10-2kg、电荷量q=4×10-5C的带电小球从两板上方的A点以v0=4m/s的初速度水平抛出,小球恰好能从M板上端进入两板之间,并沿直线运动打到N板上的B点.已知A距两板上端的高度为h="0.2" m, 不计空气阻力,g="10" m/s2。则( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025041521841.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025041521841.png)
A.小球到达M板上端时的速度大小![]() |
B.M、N两板间距d=0.3m |
C.落点B距N板上端距离L=0.2m |
D.小球到达B点时动能Ek =0.175J |
ABD
试题分析:进入电场前,小球做平抛运动,只有重力做功,所以平抛运动过程中有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504183985.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504168760.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504199644.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504215643.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504230882.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025042461231.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504277582.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504495885.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250025045731136.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002504589653.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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