Few things are more exciting than racing down a roller coaster track at super-high speeds. The suspenseful build up, the fierce wind blowing through your hair, and the dizzying rush of whirling round a loop-de-loop offer a sensational experience that’s almost impossible to match.

Ever since the very first roller coaster opened up in 1817 – “Les Promenades-Aériennes” (The Aerial Walk) in Paris – designers have been looking for brand new ways to make these theme park classics even more exhilarating. But no matter how they change their designs, the physics of roller coasters always stay the same.

So you may be wondering: “How does a roller coaster work, anyway?” Well, let’s find out.

The parts of a roller coaster

Did you know that roller coaster cars don’t have engines, or even any power sources at all? It’s true. In fact, they rely almost entirely on just two forces:

• Gravity, which pulls objects towards each other
• Momentum, which is the force gathered by motion

To start its thrilling journey, a roller coaster car needs to do one of two things: get to the top of a hill or get a powerful launch.

Those that rely on a hill to get going traditionally use a chain lift. This is a long chain or series of chains running under the track that pulls the car to the top of the hill. There’s a motor at the bottom that turns the chain loop, moving the car upwards like a conveyor belt. They also cause the clack-clack-clack noise that you might be familiar with. Once the car reaches the top, the chain releases and you start your descent.

Some modern roller coasters use a catapult-launch lift instead. These come in several forms. For example, a linear-induction motor uses electromagnets, one on the track and one under the car. A motor moves the electromagnet on the track, pulling the car behind it (though that’s a science lesson for another time). Another system uses rows of rotating wheels that grip the bottom or top of the car to move it forward.

No matter how the roller coaster car gets going, it needs brakes to slow for corners or stop at the end or for safety reasons. These brakes are usually built into the tracks rather than the roller coaster car.

The physics of roller coasters

Whether a roller coaster uses a chain lift or a catapult-launch lift, its initial ascent allows the car to build up potential energy, also known as energy of position. This is a type of energy that gets stored up inside an object because of its position in relation to other forces.

In this case, that other force is gravity, which tries to pull the roller coaster car down toward the ground. The higher the roller coaster car climbs, the more potential energy it builds because gravity can pull it down further.

When the car tips over the edge of slope, gravity causes the stored potential energy to become kinetic energy, or the energy of motion. Gravity pulls the front of the car down, causing it to accelerate. As it does, the tracks guide it in different directions.

When the car tries to go up another slope, gravity starts pulling the back of it instead of the front. This causes it to slow down. But as it climbs the slope, it starts building more potential energy. And if it has enough momentum to reach the top, that new potential energy will turn back into kinetic energy once it goes over the edge. So, you’ll race off down the slope once again.

In most roller coasters, the hills get smaller and smaller as the car moves along the track. That’s because the total amount of energy that was built up during the initial lift is slowly lost to friction between the car and the track, as well as between the car and the air.

Eventually, the energy the roller coaster car started with will run out completely. When this happens, the car will stop unless it’s pulled along by another chain or catapult-launch lift. Then, the cycle can start all over again.

Why don’t I fall out when I go upside down?

If gravity pulls you down toward the ground, you might think you’d fall out of the roller coaster car when you’re upside down in a loop-de-loop. But thanks to the physics of roller coasters, you stay safely in your seat. What’s even cooler is that this would still be true even if you didn’t have a safety harness!

This is because a loop-de-loop is a type of centrifuge. A centrifuge is an object that asserts centrifugal force. And centrifugal force causes objects that are moving in a circle to be pushed out away from the center of that circle.

At the bottom of the loop-de-loop, both gravity and centrifugal force push you down into your seat. So at this point, you might feel super heavy. At the top, gravity is still trying to pull you down. But the incredible speed of the roller coaster car means the centrifugal force of the loop-de-loop pushes you away from the middle of your circle of motion.

In other words, the loop is pushing you up into the sky with a stronger force than gravity is pulling you down. So rather than falling to the ground, you stay in your seat. The ascent up the loop-de-loop track also allows the roller coaster car to build up more potential energy. So when you’re on your way down and that potential energy is turned into kinetic energy, you start to speed up!

Keep exploring the physics of roller coasters with STEAM learning kits

The best way to learn about the physics of roller coasters is to ride one. But unfortunately, not many schools or homes have space for their own theme park. So we’ve gone ahead and packaged all of that incredible science into a fun and simple STEAM learning kit instead.

With our Creating Coasters & Zip Lines Multipack, kids aged 12-14 can explore potential and kinetic energy by designing and building their very own structures. The pack contains easy step-by-step instructions for six thrilling activities in both English and Spanish. That means your kids can experience and enjoy play-based learning in their preferred language, or even practice their second.

The Creating Coasters & Zip Lines Multipack is available online with free shipping. Order yours today and introduce your kids to the wonders of motion!