1. The problem statement, all variables and given/known data A proton is released from rest in a uniform electric field of magnitude 8x10^4 V/m. After the proton has moved 0.5 meters a) What is the change in electric potential? b) What is the change in potential energy? c) What is the speed of the proton? 2. Relevant equations U(elec)=U(naught)+qEs s=change in distance q=charge of particle E= electric field 3. The attempt at a solution I'm more or less looking for clarification of the problem... on part a), do you think he means what is the change in electric potential energy? If not, how does the electric potential change? Maybe I don't know the difference well enough. In part b) if part a) is talking about electric potential energy of the particle, does the particle gain or lose mechanical potential energy?