# Homework Help: Electrostatics question, need help

1. Feb 4, 2009

### 9giddjl

Electrostatics question, need help urgent!!

1. The problem statement, all variables and given/known data
A small metal sphere carrying a charge of -2Q is first brought into contact with sphere R Which has a charge of +Q, and then into contact with sphere S which has a charge of +2Q, and finally into contact with sphere T which has a charge of +3Q. After making contact with the three spheres, in the stated order, the charge on the sphere at T is?

2. Relevant equations

F=kqQ/d^2

3. The attempt at a solution

Honestly, I've never learnt how to do these sort of questions. I'd just like some insight on how to do these types of questions! any help is muchly appreciated ! please help, thankyou

2. Feb 4, 2009

### rl.bhat

Re: Electrostatics question, need help urgent!!

If the charged spheres are identical, the net charge will be shared equally by them. In the first case, after contact the net charge is -Q. So the charge on each sphere is - Q/2.
In similar way try the other cases.

3. Feb 4, 2009

### 9giddjl

Re: Electrostatics question, need help urgent!!

Thank you. I understand how to do the question now. The answer is +15/8 Q.