Physics
posted by MD .
A skier of mass 64 kg starts from rest at the top of an 18° slope, points her skis straight down the slope and lets gravity pull her down the slope. The slope is 65 m long. Her speed at the bottom is 15 m/s. (a) Assuming zero air resistance, what is the magnitude of the frictional force between her skis and the snow? (b) What is the coefficient of kinetic friction between her skies and the snow?

(a) Subtract her final kinetic energy (MV^2/2) from her initial potential energy (M g H). That is the energy lost to friction. Divide that energy loss by the diatance she travels (65 m) to get the average friction force, f.
(b) f = muk * cos 18 * M * g
Solve for muk 
thnks so much