1. The problem statement, all variables and given/known data You are lifting a chain straight up at a constant velocity v_0. The chain has a linear mass density λ. What is the force required to lift the chain as a function of height? 3. The attempt at a solution U = mgh = λygh The height in the potential energy is the same as the potential energy at the center of mass h = y/2 U = λgy^2/2 This is a conservative potential energy in one dimension F = -∂U/∂y= -λgy Is this correct? Can conservative forces consider objects of non-constant mass as I've done?