Pupils dilate, heart rate soars, you feel like you’re flying! Somehow you feel weightless and then twice as heavy all in a matter of minutes. You are experiencing the euphoria of riding on a roller coaster! Ever wonder why you feel all these different things? Or how roller coasters came to be?
When did people start riding roller coasters?
Historians trace the first roller coasters back to Russia in the 16th century. They designed and constructed wood-framed sleds to go down Ice Slides. They would find ice slopes reaching 70 feet high, sit on the wooden sleds, and slide down the ice. As this activity gained popularity, Russians rolled down the slopes in wooden carts during the summer. These wooden rolling carts were the first designs for roller coaster cars!
The earliest coasters were wooden with huge lattice structures and resembled railroad tracks. The oldest coaster in America still in operation is Leap the Dips at Lakemont park in Altoona, PA. Built in 1902, Leap the Dips is registered as a Historical Landmark. It boasts a 9ft drop and can reach speeds of 10mph. Coasters have certainly come a long way.
The physics behind roller coasters involve gravitational potential energy, and Newton’s laws of motion.
Firstly, to understand roller coasters you need to understand potential energy. Potential or stored energy is the energy an object possesses based on its position rather than its motion. When you ride a bike, and reach the top of the hill that is potential energy. If I hold a pencil above my head, it contains potential energy. If I drop this pencil, what happens? The potential energy is converted to kinetic energy as it falls to the ground.
What is pulling the pencil to the ground? Gravity! What is gravity? It is a force that attracts or pulls an object towards the Earth. We can stand on the ground because of gravity. The things in this room are not floating around because gravity pulls them towards the Earth.
As our roller coaster climbs the hill, its gravitational potential energy increases. The higher the car is from the ground, the more gravitational potential energy it possesses. When the car peaks at the top of the hill and starts to go down, the energy converts into kinetic energy. The car possesses kinetic energy due to gravity. As the car goes down the hill, the kinetic energy increases.
When the drop is very high, you get that feeling of weightlessness as you go down. As you plummet, gravity pulls you down while the acceleration pulls you forward. If you are going fast enough the forces balance each other out making it feel as if you are in free fall!
Newton’s first law is also in play on a roller coaster. The first law is all about inertia; an object at rest will want to stay at rest and vice versa. As you navigate the twists and turns, you get jerked around because of your body’s resistance to the change in direction, momentum, or acceleration. You might also feel plastered to your seat as you zoom down a hill – it’s all about inertia!
What about the loops? How come you don’t fall out? Centripetal Force!
As you go through the loop, the forces on your body vary as you go up and around. Besides gravity pulling down, the one thing that remains constant is a force pulling towards the center of the loop; that’s centripetal force! Even if your straps weren’t there you’d still stay in the car because of inertia.
Initial loops were circular meaning the angle of turn was constant all the way round. The downside of the circular loop was that the cars had to enter the loop at an immense speed making it uncomfortable for riders. Engineers switched to a teardrop loop design, which has a sharper turn at the top. The new shape allows the car to have the right amount of acceleration to get up and through the loop with more fun!
Engineers can do amazing things! Next time you are on a roller coaster, pay attention to how your body feels as it moves through the twists and turns. That came straight from the imaginative mind of a roller coaster engineer.
For more roller coaster information please visit the links below:
http://www.physicsclassroom.com/mmedia/circmot/rcd.cfm
http://science.howstuffworks.com/engineering/structural/roller-coaster5.htm