A problem about work Hi! I need some help with this question: Jim rides his skateboard down a ramp that is in the shape of a quarter circle with a radius of 5.00 meters. At the bottom of the ramp, Jim is moving at 9.00 m/s. Jim and his skateboard have a mass of 65.0 kg How much work is done by friction as the skateboard goes down the ramp? What I used was W=F(force) x r (displacement) F= mv^2/r = (65 kg x 9 m/s^2)/(5 m) = 1035 N W= (1035 N)(19.6 m) (To find 19.6, I used the circumference equation to find the distance down the ramp) W= 20,286 J 20.3 kJ I really do not think this is correct, and I'm trying to figure out what it means by "frictional" force. Thanks for your help!