# Paper Roller Coaster Ideas

## Introduction

Have you ever ridden a roller coaster? Have you ever wanted to design your own? There are plenty of expensive toys and even video games that will let you build your own coasters—but in this project you’ll make one out of paper and tape, and learn about roller coaster physics along the way!

## Digging Deeper

Roller coasters are all about physics! Unlike other vehicles like cars and trains, roller coasters do not have an engine that propels them along the track. Instead, they rely on gravitational potential energy*, which they gain by initially being towed up a large hill. Potential energy is “stored” because of an object’s elevation, or height off the ground. When the coaster starts going down the hill, the potential energy is converted to kinetic energy, or the energy of the motion. When the coaster goes back up another hill, it will lose kinetic energy (it will slow down) and gain some potential energy again. Some of the energy is also converted to heat due to air resistance and friction with the track, gradually causing the coaster to slow down. This process continues as the coaster goes through loops, hills, and turns, until eventually it comes back to the beginning.

Due to conservation of energy (the total amount of energy in the system must be conserved, or stay the same), the total amount of kinetic energy and energy lost due to friction can never be greater than the initial amount of potential energy that the coaster has. That means coaster designers have to make sure the coaster has enough initial potential energy to make it through the rest of the track. This places some limits on the design. For example, the coaster cannot go through a loop or over a hill that is taller than the starting hill, because going higher would require more energy than it has available. If the track is too long, friction might eventually cause the coaster to come to a complete stop.

To build a successful paper coaster, you had to take these factors into consideration. Since some energy is always lost to friction, your starting hill has to be taller than any other hills or loops in your coaster. If you had any long, flat segments, the marble might have rolled to a stop because of friction. You have to make sure your marble has enough potential energy to make it through your whole track. So if you had trouble, go back and try making your starting hill taller.

*Note that there are other kinds of potential energy, like elastic potential energy (the energy you get when you stretch a rubber band). In this project, we are only talking about gravitational potential energy.

## For Further Exploration

• Instead of using paper, you can make roller coasters from foam pipe insulation, available at a hardware store. This will allow you to make a much bigger coaster more quickly since it doesn’t involve as much cutting, folding, and taping. See the Additional Resources section for examples.