posted by John .
A skier of mass 75 kg accelerates from rest down the slope as shown in the diagram (It's a triangle with a height of 300 m, length of 400 m, and the hypotenuse is 500 m; The skier is on the hypotenuse.
At the bottom of the slope, he is travelling at 40 m/s.
What is the average force opposing his motion down the slope?
Compute the kinetic energy gain and the potential energy loss. Take the difference. That is work done against opposing forces. That equals the average force times the slope length.
Solve for the average force.