Electric Potential Energy?

Question

Part A:

A charge of +2.90 × 10^-4 C is fixed at the origin of a coordinate system. A charge of +8.35 × 10^-6 C is placed on a raisin of mass 2.65 g. The raisin is then brought from far away to a point 72.0 cm from the origin. What is the electric potential energy of the system?

Part B:

Suppose that the raisin is released from rest from its position at 72.0 cm from the origin. If no other forces act on the raisin, what will its final kinetic energy be?

Answer 1

A. PE = kq1q2/r = 30.227 J

B. Energy is conserved. KE = PE