1. The problem statement, all variables and given/known data A stone of mass 0.2kg is dropped from the top of a building 80m high. After t seconds it has fallen x meters and has a velocity of v. What is the potential energy of the stone t seconds later 2. Relevant equations The answer is 2(80 - x) = 160 - 10t^2 Using suvat: s = ut + (1/2)at^2 3. The attempt at a solution I started with PE = mgh PE = 0.2 * 10 * h PE = 2h Then I figured h = (1/2)*10*t^2 or h = 5t^2 So now I have PE = 10t^2 Not sure if I'm headed in the right direction or not.