A catapult is basically a spring-loaded launcher which uses a lever and tension to propel an object. The catapult was invented by the Greeks in 399 B.C. and used during wartime as a way to launch artillery toward an enemy target. Catapults were built strong enough to hurl heavy objects such as huge stones. Catapults can be complex or simple -- a slingshot is an example of an early basic catapult design. You can demonstrate how a catapult works by building a simple one.
Wrap one rubber band around the paper cup 1-inch below the lip of the cup until it is tight, but not bending the cup.
Hold the spoon upright by the handle with the scoop on top. Lift the rubber band while sliding the handle of the plastic spoon in between the rubber band and the cup with the back of the spoon facing the cup. Push the spoon down until the bottom of the scoop on the spoon is resting on the lip on the cup.
Sciencing Video Vault
Hold the bottom of the spoon handle against the cup as you wrap the second rubber band around the cup, with the spoon handle in between the rubber band and the cup. Position the rubber band so it is just above the very bottom of the spoon handle as you wrap. You have done this correctly if you can lift the spoon by the scoop without the cup or the rubber bands coming loose.
Pull back the scoop of the spoon toward the opposite side of the cup until it touches the lip of the cup. Place a cotton ball inside the scoop. Release the spoon to launch the cotton ball.
Do not use a Styrofoam cup which will crumble and crack. Use a 12-oz. paper cup designed to hold hot beverages for best results.
Place the spoon on the opposite side of the seam of the cup to allow more give and spring during the launch.
Never shoot projectiles toward any person.