1. The problem statement, all variables and given/known data What happens to the potential energy of a capacitor with length d when said length d is doubled? Use the formula for the potential energy of a capacitor [U = 1/(2C) * Q]. After that, refer to the work done by moving the capacitor the distance d. These two approaches should yield the same result! 2. Relevant equations U = 1/(2C) * Q, and, I guess, the traditional formula for work, W = F * d. 3. The attempt at a solution I know how to solve the first part, because C is halved when d is doubled, so the potential energy is doubled. But I have absolutely no clue as to how to even begin working on the second part. Any tips?