题目内容
用30cm的细线将质量为4×10-3㎏的带电小球P悬挂在O点,当空中存在水平向右,大小为1×104N/C的匀强电场时,小球偏转37°后处于静止状态。(sin37°=
0.6,cos37°=0.8,g=10m/s2)
(1)分析小球的带电性质及带电量;
(2)求细线的拉力。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124418303864.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/2014082412441830372.gif)
(1)分析小球的带电性质及带电量;
(2)求细线的拉力。
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124418303864.gif)
解:(1)由受力分析可知电荷带正电, (2分)
根据力的平衡条件得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241244183501946.jpg)
即有:
(4分)
(2)由力的平衡可得:
(4分)
根据力的平衡条件得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124418319557.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241244183501946.jpg)
即有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124418366794.gif)
(2)由力的平衡可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824124418381726.gif)
略
![](http://thumb2018.1010pic.com/images/loading.gif)
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