1. The problem statement, all variables and given/known data A 70.0 kg skier rides a 2700 m long lift to the top of a mountain. The lift makes an angle of 14.3° with the horizontal. What is the change in the skier's gravitational potential energy? in Joules 2. Relevant equations 3. The attempt at a solution I can't seem to find why Ef * s = mas does not work? i've tried using the equation for an answer and it doesn't seem to give me the right answer.