In roller coasters, friction is a force that opposes motion and significantly slows the cars as they move on the track. While it is easy to believe that friction is bad for the ride, it is one of the forces engineers consider in ensuring passengers have a safe ride.
In the physics classroom, students often ignore the forces of friction and air resistance while considering idealized situations, according to Encyclopaedia Britannica. However, in the real world of roller coasters, these forces play important roles.
An idealized coaster reaches its top speed at the end of the ride, where the force of gravity has converted most of the stored energy into speed. With the actual coaster, friction and air resistance oppose the speed and the motion of the car, and passengers slow toward the ride's end. As the car approaches the landing pad, it automatically applies the brakes. Brakes increase the friction, so the car stops at the exact same point with each ride.
In addition to the physics concept of friction, roller coasters teach students about forms of energy. Potential energy is stored energy, while kinetic energy is the energy of motion. The potential energy increases as the chain pulls the train to the top of the first hill. It reaches its maximum in the fraction of a second before it begins its descent. As gravity pulls the train downward, it converts potential energy to kinetic energy, increasing the speed, balancing friction and providing a thrilling ride.