Have you ever wondered how roller coasters stay on their tracks and why people don’t fall out when they are upside-down? It’s because of physics – energy, inertia, and gravity. Gravity is counteracted by the force of acceleration, which is the force that pushes you forward.
You may not have realized, but the cars on a roller coaster do not have engines to generate energy. The car climbs the first hill with the help of a lift or cable that pulls it up. This creates a supply of “potential energy” or stored energy that is used by the car to go downhill as it is pulled by gravity. The potential energy is released as kinetic energy which is what will get the car up the next hill. As the roller coaster cars travel up and down hills, motion is constantly shifting between potential energy and kinetic energy.
The higher the hill, the coaster is travelling down, the more kinetic energy is available to help it travel up the next hill and the faster the car will go. Sir Isaac Newton’s first law of motion tells us that an object in motion stays in motion until acted upon by another force. Wind resistance, sometimes called drag, or the friction of the car’s wheels along the track, are forces that can slow a coaster down. Toward the end of a ride, the hills tend to be smaller because coasters have less energy to travel upwards.
There are two main types of roller coasters – wooden and steel. The way the wheels are designed keep the cars on the track. Wooden tracks are not as flexible as steel, so wooden roller coasters tend to be less complex than their steel counterparts. Steel tracks were introduced in the 1950s. The tracks are tubular and the car’s nylon or polyurethane wheels run along the top, bottom and side of the tube which secures it to the track through intricate twists or loops.
When you travel around a turn, whether in a train, automobile, or roller coaster, you can feel yourself pushed against the outside of the car. This is a force called “centripetal force” and it helps keep you in your seat.
In a rollercoaster with a loop-the-loop, upside-down design, it’s inertia that keeps you in your seat. Inertia is another name for Newton’s first law of motion and it’s what helps press your body to the outside of the loop as the car spins around. Gravity is always pulling us toward the earth, but at the top of a loop, the acceleration is stronger than gravity and pulls upwards, counteracting the force of gravity. Take a closer look at the roller coasters you see; the loops on a coaster must be elliptical rather than a perfect circle, or the centripetal force (sometimes called g force) would be too strong for safety or comfort.
How do we know that a roller coaster is safe? Engineers, designers, and builders use industry standards and guidelines. The first “people” to ride a roller coaster are sandbags or crash-test dummies. Next, engineers and amusement park workers get to try it out. What do you think—would you want to be one of the first passengers on a new ride?
Some fun facts:
· The first free-standing rollercoaster was the Switchback Railway at Coney Island in Brooklyn, NY in 1884. Its designer and builder, LaMarcus Thompson holds several US Patents for various parts of roller coasters.
· The first high-speed rollercoaster was also found at Coney Island. Built in 1907, the Drop-the Dip was one of the first coasters to use lap restraints.
· The first tubular steel coaster was the Matterhorn at Disneyland in California which opened in 1959.
· The first coaster that completely inverted passengers was the Corkscrew, opened in 1975, at Knott’s Berry Farm in Buena Park, CA.
· The first roller coaster that allowed passengers to stand was the King Cobra at King’s Island in Cincinnati, OH. It debuted in 1984.