题目内容
(8分)如图所示,在真空中的一直角坐标系xOy平面内,有一个质量为m、电量为+q的粒子(不计重力),从原点O沿y轴正方向以初速度v0射入,为了使此粒子能够沿圆弧轨道通过定点P(a,-b),可以在坐标系xOy平面内的某点固定一带负电的点电荷,若静电力常数为k.求:该点电荷的电量Q![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241224059472283.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241224059472283.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122405978764.gif)
在图中O¢处固定一个带负电的点电荷Q,使粒子在库仑力作用下绕O¢做匀速圆周运动,其轨道半径为R.
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241224060563412.jpg)
由图知q =2a, (1分)
,(1分)
,(1分)
,(1分)
;(1分)
由牛顿第二定律得:
,(2分)
解以上各式得:
(1分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241224060563412.jpg)
由图知q =2a, (1分)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122406072493.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122406087903.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122406103547.gif)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122406119536.gif)
由牛顿第二定律得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122406134633.gif)
解以上各式得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824122405978764.gif)
![](http://thumb2018.1010pic.com/images/loading.gif)
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