A 66 kilogram skier coasts up as now-covered hill that makes an angle of 25 degree with the horizontal. The initial speed of the skier is 6.6 m/s. After coasting 1.9 meter up the slope, the skier has a speed of is 3.3 m/s.
(a) Determine the work done by the kinetic frictional force that acts on the skis.