# Velocity of two insulating charged spheres at collision

1. Jul 12, 2012

### intemk9

1. The problem statement, all variables and given/known data

Two insulating spheres have radii 0.300 cm and 0.500 cm, masses 0.200 kg and 0.700 kg, and uniformly distributed charges of -2.00 µC and 3.00 µC. They are released from rest when their centers are separated by 1.00 m.
(a) How fast will each be moving when they collide?

2. Relevant equations

3. The attempt at a solution

I know i need to use the conservation of energy for the potential and kinetic forces, but I cannot figure out how to appropriately set up the equation in order to do so.

2. Jul 13, 2012

### tiny-tim

welcome to pf!

hi intemk9! welcome to pf!

don't forget you can also use conservation of momentum

3. Jul 13, 2012

### Simon Bridge

Can you argue through the conservation of energy and momentum in words? What sort of energy does each sphere start out with, and what kind does it have at the end of the motion? Do you know the equations for kinetic and potential energy?

4. Jul 13, 2012

### nasu

I think that the question is about velocity just before collision and not after collision.
The wording is a little ambiguous. If the rest of the problem were given, I suppose it will become more clear.
For part (a) conservation of energy may be enough.