Physics of Roller Coasters

People, especially children, like the thrills involved in the roller coaster. First designed by Mr. Lamacus Adna Thompson on 20th Jan, 1885, the mechanism of this ride contains a special railroad system with tracks and cars or bogies. The interesting part of it is that the track need not be a circuit, but with pre-prepared patterns, the riding on which causes the thrill in the entire operation. To know more about the physics of roller coasters, read the paragraphs ahead.


Most riders of this amusement ride may not be aware that there is no engine for operation. Then, how does a roller coaster work? Before actually understanding the mechanism, we have to understand two words from the glossary of physics. They are potential energy and kinetic energy.

Potential Energy

Potential energy is defined as that energy that is inherent in a physical system in juxtaposition with conservative force acting on it. On the movement of an object from its position against a force, energy is expended and a potential difference is created. Upon allowing the object to return to its original position the energy supplied is recovered. The best example here is the thing which has elasticity. Due to the elastic potential energy, elastic materials regain their original position. There are different types of potential energies, like gravitational potential energy, elastic potential energy, chemical potential energy, etc.

Kinetic Energy

The additional energy, which an object obtains because of its motion, is called kinetic energy. The common example of use of kinetic energy is the movement of cycle. The rider of a cycle pedals the cycle to a certain speed and after that it moves with less pedaling on its own. The kinetic energy so obtained by the cycle is used in facing the air-friction and the resistance of the road. If a dynamo is attached to the wheels of the cycle, then electrical energy is produced. The kinetic energy so produced can be used for converting into other forms of energy. Extending the example of the cyclist, it can be observed that the kinetic energy of the moving cycle on a steep rise will be converted in to a gravitational potential energy once the cycle reaches the top point. On sliding down the slope, the cycle uses the potential energy to come down.


Roller coasters work on the principle of conversion of potential energy into kinetic energy. The cars attached do not have a self-powered motor. Instead, they are pulled by one chained with the other to the first peak of the track. On reaching the top of the first peak, the kinetic energy with which the cars are pulled becomes the potential energy. With that, the cars not only slide down, but also move up the second peak. This process is repeated in the subsequent peaks, and finally, the cars are brought to a stop with the application of brake run. A well-designed roller coaster will have enough energy to complete the entire course of the track and will come to an end on the application of brake run at the end.

Modern roller coasters have launch mechanisms, which kick off a ride with the high amount of acceleration by means of one or series of linear induction motors and linear synchronous motors, powered by hydraulic or pneumatic force. Roll back occurs when a launched train does not have enough potential energy to ascend the top of the first peak.

Under the roll back, the train comes back to the original launching place for re-launch. Some enthusiastic riders want roll back to be performed in view of the thrills involved in it. In the case of continuous circuit roller coasters, when the kinetic energy is not enough for the train to complete the travel after descending from its highest peak point, it moves forward and backward along the track until all the kinetic energy is released. After that it comes to a stop.


Most of the large roller coasters use one or more trains at the same time. They use the block system under which the track system is divided in to several sections or blocks, and only one train is allowed to enter in each block at a time. A section of track at the end of the each block is used for stopping the train if necessary to avoid collision among the trains. Sensors fixed on the block detect the movement of the trains and send signals to the computer system operating the mechanism.

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