AMASE: How Do Roller Coasters Work?

Posted on Friday, April 10th, 2020


[Princess Physics standing in front of a world Map.]

Princess Physics: Have you ever wondered where does energy come from, where does it go and more importantly, how do rollercoasters work?

[Cut to Princess Physics writing on a white board.]

[Music plays.]

[Cut back to Princess Physics standing in front of a world Map.]

Princess Physics: Hi everyone, it’s Princess Physics and today we are going to learn a little bit more about conservation of energy. So, first of all what is energy? Energy in the world of physics, just means the ability to do stuff. There are lots of different kinds of energy, but the two we’ll focus on today are kinetic energy and potential energy.

Kinetic energy is used to describe things that are in motion. A moving car, a falling tree, a ball that’s been thrown.

[Small video of a cat walking appears in corner.]

Princess Physics: Basically, anything moving has a kinetic energy.

Potential energy is when an object has energy that is stored. Like a spring that has been stretched or compressed or a pendulum that’s being held away from its midpoint or any object being held above the ground has potential energy. It’s called potential energy because the object has the potential to move somewhere or gain kinetic energy. 

The most interesting thing about energy is, it can’t be created or destroyed. It can only change the kind of energy that it is. Like potential energy to kinetic energy. This is called the law of conservation of energy.

[Cut to slide: The Law of Conservation of Energy. The total amount of energy in a system will remain constant, even after it changes forms!] 

[Music plays.]

[Cut back to Princess Physics standing in front of a world Map.]

Princess Physics: Sometimes, systems are said to lose energy when a small amount of energy is transformed into an unwanted kind. Like friction when two objects rub together, or air resistance when an object is moving through the air, or sometimes you can even lose energy in the form of sound. An example of this is a pendulum.

[Cut to video of a pendulum made from a ruler and a weight, on a wall in the rest position]

Princess Physics: You can see that the rest position of this pendulum is exactly in the middle of its path. When you bring the pendulum up here, so it is horizontal to the ground. This is where it will have the most potential energy. Because it is the furthest away from its rest position. SO, when I let go, all of the stored potential energy is converted into kinetic as gravity pushes the mass down.

[Princess physics pulls the pendulum to a horizontal position and releases it. Where it was release and where it should reach are indicated on the screen.]

Princess Physics: In a perfect system the kinetic energy would be enough to push the mass back to the where is started on the other side. Here you can see that is not the case. Because the mass is moving against a wall we lose a little bit of energy because of friction between the ruler and the wall.

[Cut back to Princess Physics standing in front of a world Map.]

Princess Physics: Now the best example of conservation of energy is of course, rollercoasters! So, when you’re on a rollercoaster you’re all buckled in and they slowly start to move you up a big hill, this is when your potential energy is increasing, because you are moving higher off the ground and working against gravity. Now this is the same as the pendulum example, except your rest position is here on the ground. All of that work that was done to push you up that hill is now stored as potential energy. This is the fun part, as soon as you let go at the top of the hill, all of your potential energy is changed into kinetic energy and you’re sent flying down the hill. But the really cool thing about rollercoasters is they are designed to have very little energy lost to friction, so the potential energy from the first big hill can actually get you through the entire track, loop-da-loops included! 

[Cut to animation of a rollercoaster.]


[Cut back to Princess Physics standing in front of a world Map.]

Princess Physics: And that’s it! Everything we love about rollercoasters is mainly due to one simple law of physics – the conservation of energy! Thanks for watching everyone, and remember – never stop learning!

[Cut to rollercoaster animation drawing with a cat on it.]


For today's Ask Me Anything: Science Edition, our very own Princess Physics tackles the question of How Do Roller Coasters Work?

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