A 5.00*10^-4 C charged mass (1.00g) is thrown upwards at a speed of 20.0 m/s and it is observed that it has gone up a distance of 15m it is moving at only 10.0 m/s. If the electric potential at the point of release is taken to be 0.0 Volts, what is the electric potential at 15 m up?