题目内容
如图所示,I、Ⅱ是竖直平面内两个相同的半圆形光滑绝缘轨道,K为轨道最低点。轨道I处于垂直纸面向外的匀强磁场中,轨道II处于水平向右的匀强电场中。两个完全相同的带正电小球a、b从静止开始下滑至第一次到达最低点k的过程,则此过程带电小球a、b相比
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250029106794474.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250029106794474.png)
A.球a所需时间较长 |
B.球b机械能损失较多 |
C.在K处球a速度较大 |
D.在K处球b对轨道压力较大 |
BC
试题分析:洛伦兹力不做功,对球a 的运动过程只有重力做正功,而对b除重力做正功外还有电场力做负功,所以二者下降到同一高度时,
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002910695483.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002910695483.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250029107261146.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002910882949.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/201408250029108981127.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140825/20140825002911163968.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目