Roller coaster: How does this exciting ride function without an engine?
You are in your favourite adventure park, waiting in the cue for your favourite ride: Roller coaster ride. Finally, it's your turn! You select a seat, fasten your seatbelt, take a deep breath and get ready to scream your heart off. The roller coaster climbs to the top of a steep hill, then eventually drops down and all of you scream in excitement! Here’s a nugget of information for you about this exciting ride: Did you know that Formula Rossa in Abu Dhabi is the world's fastest roller coaster, reaching a high speed of 149.1 miles per hour!
Well, now, let us draw your attention to another interesting fact about roller coasters: They don’t have an engine. Wait, what? You must be wondering how they run at such high speeds without an engine. Here’s a look at the scientific concepts and forces at work behind a roller coaster ride.
The science of energies
You may have studied about energy and its types such as potential and kinetic energy in your science classes. To understand why roller coasters do not require an engine, we will need to understand these terms. Potential energy refers to the stored energy that an object gains because of its position or height. Kinetic energy is the energy that an object gets as the result of its motion or speed! Imagine climbing a steep slope in a car or on a bike. You generate potential energy while climbing the hill. As you move down, potential energy is converted into kinetic energy that helps you move down the hill faster. A roller coaster also functions in a similar way.
As a roller coaster lacks engines, it must be pulled up the first big hill by a mechanical chain. As it moves up higher into the air its potential energy increases as it reaches the top of the hill. You may wonder what the role of potential energy here is. The potential energy of the roller coaster is the amount of work it will be capable of doing after being converted into kinetic energy as it declines over the hill's other side. But can a roller coaster go down a hill using only kinetic energy? What causes it to roll down that hill? It's for the exact same reason that you trip and fall: Gravity!
The science of gravity
As soon as a roller coaster peaks the first big hill, gravity takes over and the ride begins to fall at a constant pace. Gravity produces a constant downward pull on the vehicles. The coaster tracks help in directing this gravitational force and regulate the direction of the coaster cars' in going down. All that potential energy that it acquired before is converted into kinetic energy as it moves down the hill. The roller coaster speeds as it falls and gathers enough kinetic energy to carry it through the rest of the trip.
So, doesn't this require an engine? Well, no. This is because inertia eliminates the need for an engine. But what is inertia? The law of inertia states that a moving object will keep moving until it is stopped by an additional or external force. This implies that a roller coaster might keep going on forever due to the kinetic energy generated during the first hill's decline. Yet we all know that rides on roller coasters don't continue forever. This is because while the roller coaster travels loop-the-loops, bends and other hills along the course, it loses energy to other forces.
The science of friction
These other forces finally bring the roller coaster to rest, with the help of brakes near the finish of the ride. What then are these extra forces? The two most important ones are friction and air resistance. Friction is defined as the resistance caused by two surfaces in contact as they move past each other. When you ride a roller coaster, the wheels rub against the tracks generating heat due to friction. This converts the remaining kinetic energy into heat energy, finally exhausting it. In addition to this friction, the air you move through on the roller coaster also generates resistance that gradually slows down the ride.