Popsicle Stick Catapult
When you pull the arm back and let go, the rubber bands snap back and launch a pompom into the air. The harder you pull, the further it flies. That is Newton's Second Law: more force means more speed.
What you will learn
- How stored energy (stretched rubber bands) turns into movement
- Second Law: pull harder and the pompom goes further because there is more force pushing it
- What happens to the pompom after it leaves the spoon
Learn more (optional):
Parts you need
- 5 popsicle sticks
- 5 rubber bands
- 1 spoon
- 5 pompoms (for launching)
Build steps
Step 1 - Bundle the sticks and secure with two rubber bands
Stack all five popsicle sticks on top of each other. Wrap one rubber band tightly around each end to hold the bundle together.
Step 2 - Attach two sticks on top and three on the bottom
Take two more popsicle sticks and lay them on top of the bundle. Take three more and put them underneath. Loop a rubber band around all of them right in the middle of the bundle. This middle point is the pivot where the catapult arm will swing.
Step 3 - Rotate the sticks and lock them in place
Push the top two sticks and the bottom three sticks apart so they are pointing sideways, at a right angle to the bundle. Wrap another rubber band around them to hold that position.
Step 4 - Attach the spoon
Lay the spoon on the end of the top two sticks with the bowl facing up. Wrap two rubber bands around the handle to hold it firmly in place.
All done
Try it out
Place a pompom in the spoon, push the arm down, and let go. Try pulling it back further and see how much further the pompom travels.
What to notice
- The further back you pull, the more the rubber bands stretch and the further the pompom goes.
- The pompom follows a curved path through the air even though it left the spoon going up and forward.
If something does not look right
- Arm flops instead of snapping: make sure the rubber band at the middle is tight and holding the sticks at a right angle to the bundle.
- Spoon spins or slips: wrap the rubber bands closer together or add an extra one.
- Pompom goes sideways: check that the spoon is sitting straight along the arm and not twisted to one side.