题目内容
在一条直线上,从左向右依次固定A、B、C三个质量之比为mA:mB:mC=1:2:3的带电小球,小球所在的光滑平面是绝缘的。当只将A球释放的瞬间,它获得向左的加速度,大小为5m/s2;当只将B球释放的瞬间,它获得向右的加速度,大小为4m/s2;那么,当只将C球释放的瞬间,它获得向 的加速度,大小为 m/s2。
左 1
试题分析:在光滑的水平面上,小球所受重力和支持力平衡,使小球产生加速的力就是小球间相互作用的库仑力。小球A受到小球B和C的作用力分别记为
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222001771419.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222002973421.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222004127427.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222005515425.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222006904426.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222008323432.png)
对小球A有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222009509796.png)
对小球B有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222009540811.png)
对小球C有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222010429805.png)
由于
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222001771419.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222004127427.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222013908619.png)
①+②+③得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222015250805.png)
根据题意取向左为正方向,则有:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222016404668.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222017309688.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222018198647.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824222019524509.png)
![](http://thumb2018.1010pic.com/images/loading.gif)
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