Synchronised screaming, scenery dashing past and the rush of numbing air… yes, all of these may sound familiar to you if you have ridden a rollercoaster before. The first roller coaster was a train attached to a track called ‘Russes a Belleville’, that was invented in France. They had developed this idea using ice slides that were popular back in 16th and 17th century Russia. Ice slides were hills constructed out of ice that were up to 70 feet high, supported by wooden structures. People would go down them in sleds, crash-landing in a sand pile.
A rollercoaster doesn’t have its own engine. It’s only powered at the start of the ride, when it’s pulled up the first hill. This means the rollercoaster is primarily moved by gravity, force that pulls the rollercoaster down, and momentum, force that the train has while it’s moving. As the train gets to the top of the hill, the rollercoaster gains potential energy that’s stored in an object. When the train is at the top of the hill, gravity pulls the train down, accelerating the train. Potential energy is then converted to kinetic energy, energy of motion. Trains have a limited amount of energy they can store as potential energy. In theory, throughout the ride, the same amount of energy should be swapping back and forth between potential and kinetic energy, and this could go on forever - the ride would never end. However, the total energy store built up in the hill is gradually lost to friction between the train and the track, and air resistance. Rollercoasters cannot replace this loss, as they lack engines. By the end of the ride, the energy reserve is almost completely empty, resulting in the train stopping.
A brake system also allows the train to stop exactly at the end of a ride. The brakes are built into the track in the form of several clamps. When a train needs to stop, a central computer uses a hydraulic (uses power generated from liquid forced through a small tube) system that closes these clamps in on metal fins running under the train. Friction between the clamps and fins slows the train down to a stop.
There are other components to the rollercoaster. A length of chain runs under the hill that is wound around a gear at the top and bottom of the hill. The gear at the bottom of the hill is turned by a motor, and winds the train up to the top of the hill. More specifically, when the train grips onto the chain with its hinged hooks called chain dogs, the chain pulls the train to the top of the hill. At the summit, the chain releases the hooks, allowing the train to descend the hill.
In newer rollercoasters, a catapult system builds up potential energy in a short amount of time. This is done by using a linear-induction motor or rotating wheels. A linear-induction motor uses electromagnets that produce two magnetic fields - One on the bottom of the train, and one on the track - that are attracted to each other. The motor moves the magnetic field along the track, pulling the train behind it at high speed. Rotating wheels, on the other hand, are arranged in two adjacent rows along the track. The wheels grip the bottom of the train that is between them, pushing the train forward.
Accelerator coasters are even newer rollercoasters that start off fast, like ‘Rita’ at Alton Towers. These are hydraulically launched and are even faster than linear induction motors. They have several hydraulic pumps that push fluid into several accumulators, leading to the pressure build up of nitrogen gas inside accumulators. This pressure is released at the start of the ride, launching the train at high speed.
Rollercoasters are designed to be safe. They are completely controlled by computers that regulate the ride’s speed, ensure the trains don’t come too close to one another, and alert human operators to hazards. The ride would therefore never leave the station with an unsecured safety belt. The rollercoasters, like all amusement park rides, are inspected by safety experts at least once a year and more regularly and thoroughly checked by independent examiners for up to 14 hours. A 2-hour daily check is done to check for anything unusual. Therefore, the danger related to rollercoasters is not due to the rides themselves, but due to the conditions that riders already have. This is why those with high blood pressure and heart disease are suggested to not ride at all. If you are pregnant, don’t meet the height and weight requirement or have been consuming alcohol, you are putting yourself at risk as well. Science can be a thrill, but you need to stay safe.