Let's say I have a pinball (solid sphere) with a given mass and radius, and it is held back at a certain distance from equilibrium on a spring. The spring constant k is given, and the ball is then fired onto the pinball machine surface, which is tilted. How would I find the maximum height the pinball rolls to (above its initial location.)? I know I should use energy conservation, but is this the correct formula: 0.5m(vi^2) + 0.5k(yi^2) = 0.5m(vf^2) + 0.5k(yf^2)? Would yf be the same as the height at which the pinball machine is tilted or is it the distance from the spring equilibrium the pinball travels to? Thanks.