# Homework Help: Calculating electrical potential energy

1. Aug 15, 2013

### Gavinofree

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

Three equal point charges, each with charge 1.60μC , are placed at the vertices of an equilateral triangle whose sides are of length 0.600m . What is the electric potential energy U of the system? (Take as zero the potential energy of the three charges when they are infinitely far apart.)

2. Relevant equations

W = ΔU, Coulomb's Law, U_elec = qV

3. The attempt at a solution

I've drawn a diagram of the equilateral triangle with the 3 point charges. I then proceeded to adding in the force vectors appropriate to the force exerted upon each of the individual charges. I found through this process that the charge at one of the corners undergoes a vertical downwards motion when vectors are added.

The complication here is that I'm not sure how to go about this. Is it correct to set one charge where the electric potential energy is 0 and since it is 0.600m apart, this equates to the electric potential? I'm confused at the moment and would greatly appreciate it if anyone could help me out.

2. Aug 15, 2013

### voko

What is the potential energy of two equal charges q separated by distance d?