Marble Roller Coaster: Converting Potential Energy to Kinetic Energy
|Areas of Science||
|Time Required||Average (6-10 days)|
|Material Availability||Readily available|
|Cost||Low ($20 - $50
Marble Roller Coaster: Converting Potential Energy to Kinetic Energy
|Areas of Science||
|Time Required||Average (6-10 days)|
|Material Availability||Readily available|
|Cost||Low ($20 - $50)|
|Safety||Adult supervision recommended when using utility knife|
AbstractIf you'd like to investigate the physics of amusement park rides, then this project is for you. You'll build a roller coaster track for marbles using foam pipe insulation and masking tape, and see how much the marble's potential energy at the beginning of the track is converted to kinetic energy at various points along the track.
The goal of this project is to build a roller coaster for marbles using foam pipe insulation and to investigate how much of the gravitational potential energy of a marble at the starting point is converted to the kinetic energy of the marble at various points along the track.
Andrew Olson, Ph.D., Science Buddies
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Last edit date: 2020-03-13
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.
Potential energy comes in many forms. For example, chemical energy can be stored and later converted into heat or electricity. In the case of a roller coaster, the stored energy is called "gravitational potential energy," since it is the force of gravity that will convert the potential energy into other forms. The amount of gravitational energy can be calculated from the mass of the object (m, in kg), the height of the object (h, in m), and the gravitational constant (g = 9.8 m/s2). The equation is simply: gravitational potential energy = mgh.
Kinetic energy is the energy of motion. The amount of kinetic energy an object has is determined by both the mass of the object and the velocity at which it is moving. The equation for calculating kinetic energy is: kinetic energy = 1/2 mv2, where m is the mass of the object (in kg) and v is the velocity of the object (in m/s).
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 t