1. The problem statement, all variables and given/known data Jim rides his skateboard down a ramp that is in the shape of a quarter circle with a radius of 6.50 m. At the bottom of the ramp, Jim is moving at 2.82 m/s. Jim and his skateboard have a mass of 67.0 kg. How much work is done by friction as the skateboard goes down the ramp? ______J 2. Relevant equations angular velocity? + frictional force equation? 3. The attempt at a solution How is the frictional force determined from this with out the kinetic friction coefficient?