When you stretch or twist a rubber band it stores potential energy. Specifically it stores elastic potential energy—the type of energy stored when a material is deformed (as opposed to gravitational potential energy, the type you get when you raise an object off the ground). When you release it all, that stored energy has to go somewhere. If you launch a rubber band across the room, the potential energy is converted to kinetic energy, the energy of motion.

But what about putting all that stored energy to use? You can attach your rubber band to a simple machine—a wheel and axle—to build a simple rubber band–powered car. In real cars, gasoline’s chemical energy or the electrical energy in a battery is converted to kinetic energy of the moving car.

This simple toy will use a rubber band as the source potential of energy. It will take a little effort to get your machine working, as it needs some assembly. Challenge yourself to see how far your thingy can roll!

Sorry, 2 AA batteries (not included) are used for the flashing light when in motion.

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