4) [20 pts] Assume that the snowboarder represented in the accompanying figure has a velocity, v,of 15 ft/sec and that he weighs 180 lb. The value of the kinetic coefficient

of friction, L4, between the snowboard and the snow is 0.10. You may treat the snowboarder as a particle that is located 3 feet from the snow (point P in the figure). Assume that all forces in this system act on the particle.The weight of the snowboard is negligible. a) Draw a free body diagram of the snowboarder. b) Find the normal force, N, on the snowboard. c) Determine the magnitude of the acceleration, a, for the instant represented.