m = mass of the roller coaster = 500 kg
h = height of the hill = 80 m
v = speed of the roller coaster at the bottom of the hill = ?
using conservation of energy
kinetic energy at the bottom of the hill = potential energy at the top of hill
(0.5) m v² = m g h
(0.5) v² = g h
inserting the values
(0.5) v² = (9.8) (80)
v = 39.6 m/s
hence the speed at the bottom comes out to be 39.6 m/s
