# How Do Roller Coasters Work?

Three forces viz; inertial, gravitational and centripetal forces come into play while giving you a great ride on board rollercoaster. You may mentally connect a rollercoaster with a passenger train consisting of connected compartments that run on tracks. However unlike a passenger train, there is no engine or power source involved in a rollercoaster.

The 'initial lift hill' (the time when the coaster is pulled up the first hill) is done to build up a stock of potential energy. After that for most part of the ride, the rollercoaster moves by the forces of gravity and inertia. As the coaster rises up in the air, gravitational forces start to work, applying a constant downward motion on the coaster. In other words, the potential energy you build while going uphill is released as kinetic energy to take you down-hill. The top of the first hill or the highest point on the track is the place where the roller coaster's gravitational potential energy is the highest. Each time the roller coaster goes downhill, the gravitational potential energy reduces and its kinetic energy increases.
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A roller coaster is an amusement ride that looks like a passenger train but without an engine or any power source. Roller coasters are driven by forces of inertia, gravitation and centripetal force. The only time when any external force is used in a roller coaster ride is in the first lift where the roller coaster is pulled up the lift hill.

The initial life over the lift hill builds up potential energy and when the roller coaster is released down that first hill, gravitational force takes over to create kinetic energy from the already created potential energy.

An object in motion always tends to stay in motion and thus the coaster plunging down the first lift hill will remain in motion even when it goes up the track. When the coaster moves up a small track, the kinetic energy that moves it again changes to potential energy and when it moves down again it is again turned into kinetic energy to supply the necessary force to move up the next track.

The hills in the track decrease in height and the friction in the track helps in eroding the reservoir of energy built up in the initial stage, bringing the coaster to a stop finally.
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