Physics of a roller coaster
Transformation of energy
When a roller coaster starts off, it is a chain and motor movement. Once the car is at the top it possesses the most potential energy it will all ride. Potential energy is the energy of vertical position. From here gravity takes over and pulls them towards the ground.
When the coaster descends, it loses potential energy but gains kinetic energy. Kinetic energy is the energy of motion. Throughout the ride the coaster gains potential energy as it loses speed, and gains kinetic energy as it gains speed.
Different types of wheels help the coaster on different types of the track. Running wheels guide the coaster on the track, friction wheels guide it lateral, and the final set keep the coaster on the track.