A 66.1-kg skier coasts up a snow-covered hill that makes an angle of 26.1 ° with the horizontal. The initial speed of the skier is 8.78 m/s. After coasting a distance of 1.10 m up the slope, the speed of the skier is 4.86 m/s. (a) Find the work done by the kinetic frictional force that acts on the skis. (b) What is the magnitude of the kinetic frictional force?