Help on one more question

1. The problem statement, all variables and given/known data
Two particles, separated by an enormous distance, approach each other. Each has an initial speed of 3.0 X 10^6 m/s. Calculate their minimum separation, assuming no deflection from their original path. The mass of a partical is 6.6 X 10^-27 kg.

Particle charge = 3.2 X 10^-19 C

Given:
V = 3.0 X 10^6m/s
mass of particle = 6.6 X 10^-27 kg
r = ?




2. Relevant equations
E = Eprime
Fe = kq1q2/r^2



3. The attempt at a solution
EE + EK = EEprime + EKprime
Kq1q2/r + 1/2 mv^2 = Kq1q2/r + 1/2m(vprime)^2

Dont know where to go from there