Question

What happens when a roller coaster car moves down from the top of a hill?

Answer 1

Answer:

Gravitational potential energy is converted into kinetic energy

Explanation:

At the top of the hill, the roller coaster car has gravitational potential energy, which is given by:

$U=mgh$

where m is the mass of the car, g is the gravitational acceleration, h is the height of the hill.

As the car descends the hill, it gains speed (v), so it also gains kinetic energy, given by:

$K=\frac{1}{2}mv^2$

where v is the speed of the car.

The mechanical energy of the car is the sum of its potential energy and kinetic energy:

$E=U+K$

In absence of friction, the law of conservation of energy states that the mechanical energy of the car is constant. Therefore, since as the car moves down the hill the potential energy decreases (because the height, h, decreases), it means that the kinetic energy must increase (and this is wy the speed increases). So we can say that gravitational potential energy is converted into kinetic energy.

Answer 2

When the roller coaster moves down from the top of the hill, all of its stored potential energy is converted into kinetic energy to move it and when it goes back up the hill it turns kinetic into potential.