Abstract
This is a really fun project even if you don't like going on roller coasters yourself. You'll build a roller coaster track for marbles using foam pipe insulation and masking tape, and see how much of an initial drop is required to get the marble to "loop the loop." It's a great way to learn about how stored energy (potential energy) is converted into the energy of motion (kinetic energy).Objective
The goal of this project is to build a roller coaster for marbles using foam pipe insulation and to investigate how much height is needed in order for the marble to run through a loop of fixed size.
Introduction
Slow and clanking, the string of cars is pulled up to the crest of the tallest point on the roller coaster. One by one, the cars start downhill on the other side, until gravity takes over and the full weight of the train is careening down into curves, twists, and turns. The roller coaster is a great example of conversions between potential energy (stored energy) and kinetic energy (the energy of motion). As the cars are being pulled up to the top of the first hill, they are acquiring potential energy. The chain that pulls them up the hill works against the force of gravity. At the top of the hill, the cars' potential energy is at it's maximum. When the cars start down the other side, this potential energy is converted to kinetic energy. The cars pick up speed as they go downhill. As the cars go through the next uphill section, they slow down. Some of the kinetic energy is now being converted to potential energy, which will be be released when the cars go down the other side.
You've probably noticed that the first hill on the roller coaster is always the highest (unless the coaster is given another "boost" of energy along the way). This is because not all of the potential energy is converted to kinetic energy. Some of the potential energy is "lost" in other energy conversion processes. For example, the friction of the wheels and other moving parts converts some of the energy to heat. The cars also make noise as they move on the tracks, so some of the energy is dissipated as sound. The cars also cause the supporting structure to flex, bend, and vibrate. This is motion, so it is kinetic energy, but of the track, not the cars. Because some of the potential energy is dissipated to friction, sound, and vibration of the track, the cars cannot possibly have enough kinetic energy to climb back up a hill that is equal in height to the first one. The way that physicists describe this situation is to say that energy is conserved in a closed system like a roller coaster. That is, energy is neither created nor destroyed; there is a balance between energy inputs to the system (raising the train to the top of the initial hill) and energy outputs from the system (the motion of the train, its sound, frictional heating of moving parts, flexing and bending of the track structure, and so on).
You can investigate the conversion of potential energy to kinetic energy with this project. You'll use foam pipe insulation (available at your local hardware store) to make a roller coaster track. For the roller coaster itself, you'll use marbles. There are as many possible variations to this project as there are twists and turns on a great roller coaster ride, but a good place to start is to see how much initial height you need in order to have your marble successfully navigate a loop in the track.
You'll use the same size loop for each of your tests, but you'll add (or subtract) track before the loop so that you can change the initial height where the marble starts. For each track configuration, you should try at least 10 separate tests with the marble to see whether it can loop the loop or not. You should also measure the slope of each track configuration. An easy way to think about the slope is the expression rise/run (see the illustration below). The rise is the height of the starting point, and the run is the horizontal distance from the starting point to the beginning of the loop.
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| The illustration above shows how to measure "rise" and "run" in order to calculate the average slope of the track leading in to the loop. |
How much height (rise) will be required to successfully navigate a given loop size? A foam roller coaster for marbles is easy to build, so try it for yourself and find out!
Terms, Concepts and Questions to Start Background Research
To do this project, you should do research that enables you to understand the following terms and concepts:
Questions
Bibliography
Materials and Equipment
To do this experiment you will need the following materials and equipment:
Experimental Procedure
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Note: use the utility knife with care. A fresh, sharp blade will make cutting the insulation easier. |
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| The illustration above shows the cross-section at one end of the foam pipe insulation. |
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| The illustration above shows two different roller coaster tracks for marbles. How much height is needed at the starting point in order for the marble to loop the loop? |
Variations
Here are just a few of many possible variations on this project. Perhaps these will stimulate your thoughts about other experiments you could try:
Credits
Andrew Olson, Ph.D., Science Buddies
Last edit date: 2007-09-06 11:00:00
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