# Finding the distance between two charges

1. Sep 9, 2015

### watabi

1. The problem statement, all variables and given/known data
The potential energy of a system of two charges (q1 = 5.0 µC and q2 = 3.3 µC) is 0.37 J. What is the distance between the charges?

2. Relevant equations
U=(kq_0q)/r --> r=U/(kq_0q)

U=V/q_0

V=0.37J
q1 = 5.0 µC
q2 = 3.3 µC

3. The attempt at a solution

So I was going to use equation 2 but I have two charges involved and that one only asks for q_0.
Do I calculate the change of the charge and use that for q_0?

2. Sep 9, 2015

### LittleMrsMonkey

V is potential.
U is potential energy.

3. Sep 9, 2015

### watabi

Wow, that cleared up a lot so,

r= 0.37J/((8.99e9)(5e-6)(3.3e-6)) ?

4. Sep 9, 2015

### LittleMrsMonkey

Try solving for r again,you've made a mistake.

5. Sep 9, 2015

### watabi

Was it the micro?

6. Sep 9, 2015

### LittleMrsMonkey

No.And it's the correct equation.The fraction is mot correct,though.

7. Sep 9, 2015

### LittleMrsMonkey

Seeing it in this form might help you: $U=\frac{q_1q_2}{r}$
So,does $r=\frac{U}{q_1q_2}$?

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