A 1200 kg frictionless roller coaster starts from rest at a height of 19 m. What is its kinetic energy when it goes over hill that is 13 m high?

10.85 m/s

Explanation:

m = 1200 kg, h1 = 19 m, h2 = 13 m

Let v be the velocity

Use the conservation of energy

Potential energy at 19 m = Potential energy at 13 m + kinetic energy

m x g x h1 = m x g x h2 + 1/2 mv^2

m x g (h1 - h2) = 0.5 x m v^2

g (h1 - h2) = 0.5 v^2

9.8 (19 - 13) = 0.5 x v^2

v = 10.85 m/s