1. The problem statement, all variables and given/known data A cylinder rolls without slipping down a hill. It is released from height h. What is its speed when it come down? The cylinder mass may be completely concentrated on the radius R, which is the radius of the cylinder. http://i.imgur.com/Ge3x1nu.png 3. The attempt at a solution The answer is supposed to be v=√(gh) but my calculations give; At the top the potential energy is E=mgh and at the end(h=0) all energy has become kinetic energy since no friction/air drag is acting. Thus mgh=(1/2)mv^2 <--->v=√(2gh). Why is this wrong??