On planet Tehar, the free-fall acceleration is similar as that on Earth, however there is as well a strong downward electric field which is uniform close to the surface of planet. A ball of 1.99 kg having a charge of 4.95 µC is thrown upward at a speed of 20.1 m/s. It strikes the ground after an interval of 4.10 s. Find out the potential difference between the beginning point and the top point of the trajectory?