I need to build a small catupult to launch a tennis ball, but i have no clue where to start. Please help me?

Question

I need to build a small catapult for physical science class and it has to throw a tennis ball at least 2 yards....does anybody have any ideas for me, because this has to be made from scratch.....please help, it's due tuesday!

Answer 1

take a PVC tube (about 2 feet long with a diameter slightly larger than a tennis ball) and glue a bottom at one end. saw 2 slits about 0.2 inch wide and 5 to 6 inch long in the tube just above the bottom you glued in, along-side the tube so you can put a small piece of wood (or a pencil) through the tube.

now get a spring (best is a spiral spring) and mount (e.g. glue) a round lid with the inner diameter of the tube on one side of the spring (the lid must be moveable within the tube).

put the spring in the tube on the bottom, the lid showing to the open end of the tube.

press the spring down until you can lock it with 2 small wooden pieces, one on each side through the 2 slits. put a tennis ball into the tube and then remove very fast both wooden pieces on both sides - the tennis ball will be catapulted out of the tube.

p.s. the length of the 2 slits depend on the length of the compressed spring.

i think this will work pretty fine :)