Question

A skier (mass m) has the velocity v_A = v₀ at point  A of the cross country course Although he tries hard not to lose velocity skiing uphill, he reaches point B with only a velocity vB = 2 v₀/5. Skiing downhill between point B and the finish C he again gains speed and reaches C with v_C = 4 v₀. Between B and C assume that a constant friction force acts due to the soft snow in this region; the drag force from the air on the skier can be neglected. Calculate the work done by the skier on the path from A to B (here the friction force is negligible). Determine the coefficient of kinetic friction between B and C.

Answer 1

in order to calculate the work done by the skier on the path form A to B we use the work -energy theorem :

Now we apply the work-energy theorem between points B and C, where the work of the friction force is given by −Rl_BC

The result is valid only for µ ≥ 0