The Physics of Roller Coasters!

Contributor: Jay Gregorio. Lesson ID: 13303

There are two types of amusement park riders - those scared of roller coasters and those who aren't! Whether you like the thrill of roller coasters or not, you can always have fun with physics!



learning style
Kinesthetic, Visual
personality style
Grade Level
Middle School (6-8), High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!

  • Have you ever heard of National Roller Coaster Day?

Yes, it is celebrated in America every 16TH of August! People who love roller coasters gather at amusement parks for exciting rides ... with a few screams!

roller coaster

On August 16, 1898, the first vertical loop rollercoaster was patented by Edwin Prescott from Massachussettes. Roller coasters existed before this, but the early simple designs resembled train cars on a track.

Prescott created his Loop the Loop roller coaster, which was operated in Coney Island, New York until 1910:

Loop the Loop roller coaster

Image from the Library of Congress, via Wikimedia Commons, is in the public domain.

Its design was not a great success. Fortunately, a lot of new inventors followed in his footsteps and finally made the vertical loop roller coaster the adrenaline rush of excitement we know today!

Let's discover the physics behind the engineering and construction of roller coasters!

  • Did you know that the very first roller coaster in Coney Island in 1884 ran at a speed of 6 miles per hour on gentle slopes?

Riders of today would yawn during this ride and wonder where the thrill is!

It does not compare with the 128 miles per hour top speed of Kingda Ka, the tallest and fastest roller coaster in the United States located in Six Flags Great Adventure, Jackson, New Jersey! (2020)

  • So, what makes roller coasters exciting?
  • What is the physics behind the thrill?

Mechanical Energy

Before you go deeper into the analysis of how roller coasters work, it is imperative that you know the types of energy involved in the process.

Mechanical energy is a term used to describe the energy possessed by an object due to its position and motion. This energy allows an object to do work or to perform a certain function.

All energy has a standard unit of measurement called the joule (J).

There are two types of mechanical energy:

  • Potential Energy (PE) is the energy of an object due to its relative position from a point. It is also called stored energy.

This means that if you are dropping an object, the higher your drop point is, the greater the potential energy of the object.

  • Kinetic Energy (KE) is the energy of an object due to its motion.

Every moving object with mass has kinetic energy. It is dependent on how heavy the object is and how fast it is moving.

This means that when an object is dropped from a height and starts moving downwards, it gains kinetic energy.

To better understand mechanical energy and how it works, you can explore Mechanical Energy from the Physics Classroom.

Energy Transformations in Roller Coasters

When a roller coaster moves, heat is generated by the wheels as they come in contact with railways. Sound is also produced in the process. These are both examples of energy that is produced and then lost when a roller coaster runs.

For the purpose of simplifying this analysis, however, we will treat the total energy of a roller coaster as conserved. The word conserved is a term used in physics to describe something that remains the same, nothing is created nor destroyed.

Previously, you learned about the two types of mechanical energy: potential energy (PE) and kinetic energy (KE).

When roller coasters run, there is a transformation within these two types of mechanical energy. This means that some potential energy becomes kinetic energy and kinetic energy becomes potential energy.

Nevertheless, the total amount of energy is conserved - it is the same. In expression, that looks like this:

Mechanical Energy (ME) = Potential Energy (PE) + Kinetic Energy (KE)

Imagine a roller coaster starting its journey on top of the hill.

  • What type of mechanical energy do you think it possesses when it is at rest?

Yes, potential energy!

When the roller coaster is at rest on top of the hill, it has the maximum potential energy but zero kinetic energy. Because mechanical energy is the sum of both, the value of the potential energy is also the total mechanical energy:

diagram 1

Now, imagine the roller coaster is approaching the lowest part of the track.

  • Do you think there is potential energy?
  • How about kinetic energy?

If you answered that it has both, you are correct!

When the roller coaster starts moving downwards, it will start to speed up. The process of gaining speed means that kinetic energy is increasing.

This is what transformation of energy looks like. Some of the potential energy was transformed into kinetic energy when the roller coaster started moving.

However, adding the amount of potential energy and kinetic energy at every point in the roller coaster's motion should give you the same amount of mechanical energy - it should be conserved:

diagram 2

Looking at both of the above diagrams again.

  • Is there a point where the kinetic energy is greater than the potential energy?

The answer is yes. When the roller coaster is at the very bottom of the track, the kinetic energy becomes the maximum value while the potential energy approaches zero value.

The mechanical energy within this system is the same at any point (ignoring other means of energy such as heat and sound).

In the Got It? section, you will review these basic concepts and test how much you learned! Move on whenever you're ready.

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