题目内容
如图所示,两根细线中的拉力分别为T1、T2,现在使A、B带上同种电荷,此时上下两根细线的拉力分别为T1′、T2′则( )
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426621369.png)
A.T1′=T1,T2′=T2 | B.T1′>T1,T2′>T2 |
C.T1′=T1,T2′>T2 | D.T1′<T1,T2′<T2 |
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426621369.png)
带电前:对B有:
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426783961.png)
T2=GB
对AB组成的整体有:
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426782305.png)
T1=GA+GB
带电后:对B有:
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426935670.png)
=F电+GB
对整体:
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426932964.png)
T′1=GA+GB
综上所述:T1=
,T2<
故选:C
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426783961.png)
T2=GB
对AB组成的整体有:
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426782305.png)
T1=GA+GB
带电后:对B有:
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426935670.png)
T | ′2 |
对整体:
![精英家教网](http://thumb.1010pic.com/pic2/upload/papers/20130925/201309251844426932964.png)
T′1=GA+GB
综上所述:T1=
T | ′1 |
T | ′2 |
故选:C
![](http://thumb2018.1010pic.com/images/loading.gif)
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