posted by Anonymous .
A child and sled with a combined mass of 40.0 kg slide down a frictionless hill. If the sled starts from rest and has a speed of 9.0 m/s at the bottom, what is the height of the hill?
Use conservation of energy. The mass won't matter; it cancels out of the energy conservation equaiton.
M g H = (1/2) M V^2
Solve for H, in terms of V.