See attached diagram.
Your cousin Throckmorton skateboards down a curved playground ram. Treating Throcky and his skateboard as a particle, his center of mass moves through a quarter-circle with a radius R = 3.0 m (see figure below.) The total mass of Throcky and his skateboard is 25.0 kg. He starts from rest and there is no friction. (a) Find his speed at the bottom of the ramp. (b) Find the normal force that acts on him at the bottom of the ramp. (c) Suppose that the ramp is not frictionless and that Throcky's speed at the bottom is only 6.00 m / s. What work was done by the friction force acting on him?© BrainMass Inc. brainmass.com March 21, 2019, 7:10 pm ad1c9bdddf
Problem with work, energy and centripetal force is solved.