physics
posted by ann .
A child and sled with a combined mass of 59.0 kg slide down a frictionless slope. If the sled starts from rest and has a speed of 3.40 m/s at the bottom, what is the height of the hill?

mass not relevant
(1/2) m v^2 = m g h
mass cancels
v^2 = 2 g h
v = sqrt (2 g h)
or
h = v^2/(2 g)