题目内容
如图所示,A,B是系在绝缘细线两端、带有等量同种电荷的小球,其中
.1 kg,细线总长为20 cm,现将绝缘细线绕过固定于O点的光滑定滑轮,将两球悬挂起来,两球平衡时,OA的线长等于OB的线长,A球依于光滑绝缘竖直墙上,B球悬线OB偏离竖直方向60○,求B球的质量和墙所受A球的压力(g取10 N/kg). ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241632262984629.jpg)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163225939485.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241632262984629.jpg)
m="0.2Kg" ![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163226469550.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163226469550.png)
试题分析:对B受力分析并正交分解则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241632267971485.png)
可得:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163227171484.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163227639793.png)
由A:受力分析并正交分解则:
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/201408241632279821549.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163228419682.png)
![](http://thumb.1010pic.com/pic2/upload/papers/20140824/20140824163226469550.png)
点评:本题考查了物体的受力分析并通过正交分解求物体的受力。这是典型的受力分析题,利用平衡很容易建立等式求解。
![](http://thumb2018.1010pic.com/images/loading.gif)
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