1. The problem statement, all variables and given/known data A ball has a diameter of 25.4 cm and a mass of 566 g. It can be approximated as a hollow spherical shell. Starting at rest, how long will it take to roll 10 m down an an incline of 30 degrees if it doesn't slip? 2. Relevant equations Energy conservation I = 2/3 mr^2 3. The attempt at a solution I manage dto find the final velocity ( I think it is 7 m/s), but not sure where to go from here. The only equation I have to solve for time involves angular acceleration ( α = Δω / Δt) which I also need to know time for. I also don't know the number of rotations this took.