题目内容
如图,带电粒子P所带的电荷量是带电粒子Q的3倍(不计重力),它们以相等的速度v0从同一点出发,沿着跟电场强度垂直的方向射入匀强电场,分别打在M、N点,若OM=MN,则P和Q的的质量之比为( )
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241922406965244.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241922406965244.jpg)
A. 3:4 | B.4:3 |
C. 3:2 | D.2:3 |
A
试题分析:P、Q两粒子在电场中做类平抛运动,水平方向做匀速直线运动,竖直方向做匀加速直线运动,
OM=MN,则
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192240743533.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192240993522.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192241258521.png)
竖直方向做匀加速直线运动,根据
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192241586645.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192241835812.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192242163654.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241922425061444.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192243099574.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824192243582682.png)
故选A
点评:当粒子沿着与电场强度垂直的方向射入电场的运动是类平抛运动,根据类平抛运动的基本规律解题.
![](http://thumb2018.1010pic.com/images/loading.gif)
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