Question

What happens when a roller coaster car moves down from the top of a hill? A.Potential energy is transformed into electrical energy. B.Potential energy is transformed into only kinetic energy. C.Kinetic energy is transformed into electrical energy. D.Kinetic energy is transformed into potential and thermal energy. E.Potential energy is transformed into kinetic and thermal energy.

Answer 1

Answer:

E.Potential energy is transformed into kinetic and thermal 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 acceleration due to gravity and h is the height of the car from the ground.

As the car moves down, its height h decreases, while its speed v increases: therefore, potential energy is converted into kinetic energy:

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

where v is the speed of the car.

However, we must also take into account the force of friction between the wheels of the car and the roller coaster track. This force slows down the car, and so some of the car's energy is actually "lost" and converted into thermal energy (which is due to the friction between the car wheels and the track).

Answer 2

The car gains kinetic energy in the form of momentum as it travels down the hill. It also creates thermal energy through friction.