Rubber bands can store enormous amounts of potential energy, at least as far as toy cars are concerned. When wrapped around a rigid axle attached to wheels, a rubber band can create enough torque to propel your toy car forward at impressive speeds.
Building a self-propelled car that can make the most of this stored energy is a relatively simple matter, requiring no more than some simple tools and materials and a little free time.
Cut out a 5-inch by 6-inch square of cardboard, and then cut a 2-inch wide and 1.5-inch notch into one of the 5-inch sides. Throw away the notch.
2
Thread the skewer across the notch by sticking it through the cardboard's corrugated edges. The skewer should cross the open space left by cutting out the notch.
3
Put a CD onto each protruding end of the wooden skewer, outside the cut out notch. Cement them to the skewer with poster putty.
4
Stick a thumbtack through the skewer, centered in the middle of the notch.
5
Stick the other two thumbtacks next to one another, spaced an inch apart and positioned at the un-notched 5-inch side of the cardboard.
6
Wrap one end of the rubber band around the thumbtacks in the cardboard and the other end around the skewer-bound thumbtack.
7
Twist the skewer in a circular motion toward the cardboard-stuck thumbtacks, which will wind up the rubber band. After two complete revolutions, set the car down on a flat surface, and release it. The stored energy of the rubber band will rotate the tires and propel the car forward.
