Make a Marble Run
In this science activity, kids will use recycled cardboard tubes to create their own marble runs to explore potential and kinetic energy.
Potential energy is the energy that is stored in an object. An example of potential energy is a stretched-out rubber band -- the farther you stretch it, the more potential energy it has. Another example is a marble teetering at the top of a marble run!
Kinetic energy is the energy of an object in motion. When the rubber band is released and pours out all that energy it had stored up, or when the marble begins to fly down the marble run, that energy is kinetic energy. So – potential energy is the energy that is saved up in still objects, and kinetic energy is the energy that pours out of moving objects (energy in motion).
Gravity and potential energy are related. (Remember gravity? It is the force that pulls everything down toward the earth.) Think about a marble sitting at the top of a ramp -- when you bump it ever so slightly and it starts to roll, what happens? It starts to roll faster and faster down the ramp, right? (But if you did this same experiment on a flat surface, the marble would barely move, right?) It is gravity that is pulling the ball down the ramp. So that marble teetering at the top of the ramp has the potential energy of gravity -- which is the force that will pull it down the ramp with no effort from you whatsoever (that is, once you've tipped it onto the ramp).
Marbles are choking hazards for children under the age of 3, so take precautions to keep marbles from rolling into odd places and getting into the hands and mouths of little ones.
- Cardboard tubes (paper towel tubes for smaller segments, gift wrap tubes for larger)
- Painter's tape
Using painter's tape to protect your walls, tape the tubes end to end at a slightly sloping angle against a wall. If you would like to create a zigzag or other more complex route with the cardboard tubes, you can experiment with cutting notches in the ends of the tubes so that a marble can drop down from one tube into the next one, and so on.
Place a paper cup directly below the end of the last cardboard tube.
Place the marble into the first tube and observe as the marble goes down through the run and into the cup! (You may need to try this a few times and adjust your ramps to get the marble to go all the way through.) Did you have to push the marble to get it all the way through the run? No, because gravity helped you out!
How can you increase the energy in your marble to make it go faster through the marble run? Try increasing the incline of the first few cardboard tubes and rolling the marble through again.
How can you decrease the amount of energy in your marble to make it slow down or even stop? Demonstrate by decreasing the incline of the first few cardboard tubes, making them lay almost flat. Roll the marble through one more time.
If you have a large group of kids, try splitting up into two or more teams to race your marbles.