Physics Project #2
Build a catapult that is less than one meter in height and less than one kilogram in weight. The catapult has to be able to shoot a grade A large egg over a one-meter tall wall.
Note: the drawing is not drawn to skill.
Arm ½ inch PVC pipe
Base and sides ½ inch PVC pipe
Rotation of the arm 2-inch hinge
Seat of the egg badminton ball
Joints / connectors ½ inch PVC joints (Tee and Elbow)
Others screws & rubber bands
4 1 ft 4 ft
2 0.5 ft 1 ft
2 1.25 ft 2.5 ft
2 0.25 ft 0.5 ft
3 0.5 ft 1.5 ft
1 1.75 ft 1.75 ft
Total length of pipe needed: 11.25
Elbow Shaped 6
Tee Shaped 4
2-inch hinge 1
Wide Rubber Bands 1 bag (from Wal-Mart)
Screws 1 & those required to attach the hinge
See diagram below for a detailed look:
Tip: In order to make sure the pipes are securely connected with the joints, use a hammer and gently tap the ends.
This is what we ended up with. With the pieces in the correct places, there shouldnt be any extra items left.
For the best result and the most strength, the rubbers are looped.(Doubled) (See diagram.)
Use two strands of rubber bands and loop them with two other rubber bands.
(For a simpler understanding of how we use the rubber bands, the drawing above shows only one band looping the other. However, the actual design has two bands looping two other rubber bands. )
Now that the bands are prepared, loop the ends of the bands onto the pipes. Attach the ends on the top of the stopper (around the arm). Then another (a shorter length) attached on the top of the helper.
Many use cups or bottle tops. We had a very different idea! We use the badminton ball (with the top removed) and used it as our seat. It only needs a half-inch screw to attach it securely on the head of the arm of the catapult.
Copyright © 1995 Mr. Lewis Classroom for Physics & Biology. All rights reserved.