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Marble Roller Coaster
Can your marble go the distance? Create your very own roller coaster track and watch your marble take a death-defying leap! Air bags not included!
What you need
- 2 Flexible plastic/rubber tubes (4cm in diameter)
- Stanley knife or craft knife (adult supervision required)
- Sticky tape
- A pile of books or boxes
- Toy cars
- Tape measure
What to do
Safety: This experiment requires adult supervision. Do not handle a knife yourself at any time.
- Ask an adult to cut one of the tubes in half (length ways) to make two U-shape lengths of plastic. Repeat this step for the second tube.
- Attach all four pieces end-to-end with the sticky tape to make one long track. Hint: make the joins as smooth as possible so there are no uneven bumps in your track.
- Attach one end of the track to a shelf or desk using the sticky tape.
- Curl the other end of your track slightly; just enough to make the marble travel upwards. Support this end of the track with a few books or small boxes.
- Tape the tubing down to the floor to secure everything in place.
- Place the toy cars at the lower end of the track for the marble to jump over.
- Find the spot on the ground that is directly below the beginning of the track.
- Measure the vertical distance between this spot and the beginning of the track. This is the track’s “rise”.
- Measure the horizontal distance between the same spot and the lowest point of the track. This is the track’s “run”.
- Place a marble at the top of the track and let it roll down.
- Change the ‘rise’ length while keeping the ‘run’ length constant. Repeat Step 10.
- Change the ‘run’ length while keeping the ‘rise’ length constant. Repeat Step 10. Which of these two properties affects the path of the marble the most?
When the marble is placed at the top of the track, it has potential (or stored) energy. As it rolls down the track, this potential energy is converted into kinetic (or movement) energy. If the marble has enough kinetic energy when it is launched off the end of the track, it will successfully jump over the cars.
The amount of potential energy in an object depends on its height. The higher you place an object, the more potential energy it has. Potential energy is converted into kinetic energy because it follows the Law of Conservation of Energy, which says that: energy cannot be created or destroyed but can change from one form to another. The higher you place the marble to start, the more kinetic energy it will have when it reaches the bottom and the further it will travel.
Since potential energy is only dependant on a change in height, changing the 'run' should have little to no effect on how far the marble travels.
The same principles apply to a real roller coaster. Before a roller coaster is launched, it is slowly pulled up to the highest part of the track by a motor-driven chain. The energy used to pull the coaster up is stored in the cars as potential energy. After the cars have reached their highest point and they begin their rapid journey downwards, the potential energy is converted back into kinetic energy. The bigger the drop in height, the faster the roller coaster will go.
NB: You may observe the marble travelling a shorter distance when you increase the run. However, this is usually due to the added friction of the marble against the track. If there is too much friction, some of the potential energy is transferred into heat energy instead of into kinetic energy. If this happens to you, try to reduce the friction of the track by smoothing out the surface or using a thin lubricant.
Try launching marbles with different sizes and weights. Can they all still jump over your toy cars? Why does or doesn't the size of the marble affect how far it travels?
Did you know?
"The Cannon Coaster", (a roller coaster ride in the U.S.A. from the early 1900s) attempted to have the cars leap over a gap in the tracks. At their highest point, the cars were supposed to exit a large, wooden cannon with enough speed to jump the gap. However, differences in passengers' weights would sometimes cause crashes. Luckily, the designers only ever tested the idea with sandbags instead of people. They eventually filled in the gap in this ride before it was open to the public.