There are two charges on a table. Both of them are point charges. Let's call them charge A and charge B. Charge A has a charge of 8(mu)C and Charge B has a charge of 8(mu)C as well. Charge B is in uniform circular motion around Charge A, which is at the center. Charge B is moving at a velocity v and has mass m. Derive an expression for the radius of the circle made by B, which is in uniform circular motion in terms of k,q, m and v.
Hint: Equate the forces. Free-body diagrams are pretty useful for this problem.