A 4.0g object carries a charge of 20uC. The object is accelerated from rest through a potential difference, and afterward the ball is moving at 2.0 m/s. What is the magnitude of the potential difference? I know i have to use the law of conservation Potential_initial + KE_initial = Potential_final + KE final Potential_initial + 0 = 0 + KE final but I dont know what to do after this. can some one give me any pointers?