calculating workdone due to friction and air resistance....HELP!!!! 1. The problem statement, all variables and given/known data this is my 1st post and i dont really no if i should put the whole question, so i will...just to make sure i get some help! A skier of mass 72kg, initially at rest, reached a speed of 32ms/1 at the bottom of the ski run length of 1500m that was 120m lower at the bottom than the top. calculate: the loss of potential energy the gain of kinetic energy of the skier the work done against fiction and air resistance the average force opposing the motion of the skier Its mainly the last 2 questions that im having trouble with. 2. Relevant equations 3. The attempt at a solution i tried the 1st two questions and when i came to the next two i got stuck. 1st of all i tried Work done= force * distance moved and but in order to get the force i then used the equation F=m*a, and in order to get 'a' then used SUVAT equation v2=u2+2as and its around here in which i got stuck becasue of all the numbers! Please help me! thanks in advanced!