# The Thrill of Physics

Roller coaster at Coney Island, Cincinnati

Summer is here (in the northern hemisphere) and that means that many of us will be heading to an amusement park for some good ole’ fashioned fun. I am a traditionalist when it comes to the thrill rides in amusement parks. I prefer the roller coasters that allow me to sit facing forward. Riding backwards and lying down, swinging my feet above the ground, or doing corkscrews doesn’t appeal to me. Plus these types of rides tend to make me sick to my stomach. It’s not that I am scared of these rides- just last year I went on a corkscrew steel rollercoaster that had complete upside down loops and vertical/horizontal loop curves. It was the worst 75 seconds of my life!

The flip-flap. Roller coaster type of ride, with a loop in it, Coney Island, N.Y., c1900.

What I love about roller coasters is the excitement of riding fast and feeling physical forces acting on my body. Riding a roller coaster gives you the first-hand experience of physics. As you go around a curve and feel yourself pushed against the outside of the car- that is centripetal force.

It is inertia that helps to keep you in your seat as you travel upside down around a loop. This force pushes you to the outside of the loop as you go around.  Gravity and acceleration are also at work.  Gravity is pulling you toward the earth, at the very top of the loop the acceleration force is stronger than gravity and is pulling upwards. This causes the brief feeling of weightlessness at the top of the loop.

Son of Beast" roller coaster at King's Island amusement park, Mason, Ohio . Photograph by Carol Highsmith

Roller coasters also teach us Newton’s First Law of Motion, “an object in motion tends to stay in motion, unless another force acts against it.” Generally speaking, a roller coaster does not have an engine to generate energy. A lift or cable pulls the coaster up the first hill and from there it builds a supply of potential energy. That is why most roller coaster rides start off with a climb up a big hill. As it begins to descend the hill, the potential (stored) energy is released as kinetic energy, which is what will get the coaster to go up the next hill. Throughout the ride the coaster travels up and down hills, shifting between potential and kinetic energy. You might notice, as the ride approaches the end, the hills tend to get lower. This is because the coaster has less energy to get up them.

If you are interested in learning more about the the science and history of roller coasters, or want to aquire  fun facts that you can share with your friends and family see our Everyday Mysteries- Why don’t I fall out when a roller coaster goes upside down?