1. The problem statement, all variables and given/known data I'm trying to figure out why potential energy decreases in this situation http://imgur.com/9PfjRVE [Broken] 2. Relevant equations ΔU = FΔy 3. The attempt at a solution If I define up to be positive, and ΔU = FΔy. In this picture, force is pointing down (so it is negative) and the height decreases so Δy is negative. Then ΔU = (-F)(-Δy) = FΔy. So then change in electric potential energy is positive, which means it should be increasing. But in the picture it says that U decreases.