A skier of mass 75 kg accelerates from rest down the slope as shown in the diagram. At the bottom of the slope, he is traveling at 40 m/s. What is the average force opposing his motion down the slope? (Use g = 10 N/kg)
Please help me solve the question above.
This is what I've tried:
P.E at the top = 75 * 10 * 300 = 225 000 J
K.E at the bottom = (1/2) * m * v^2 = 0.5 * 75 * 40^2 = 60000 J
Energy lost in friction: 225000 - 60000 =165000 J (work done in opposing motion)
Work done = force X distance 165000 = f X 500
165000/500 = f
f = 330 N
Is that correct?