( Stick Catapult for ages 8+)
Catapults have been an important military technology for hundreds of years, and can be traced back to 400 B.C.E. in ancient Greece.
Even though they have been around for so long and now there are so many different kinds, the basic science behind how catapults work has stayed pretty much the same.
The video above shows a fun way to build a very simple catapult with just a few simple steps. Here’s how you do it:
8-10 popsicle sticks
5 rubber bands
- Stack all but 2 of your popsicle sticks together.
- Using a rubber band, bind the stacked sticks together by wrapping the band around one end.
- Repeat step 2 for the other end of the stacked sticks.
- Have an adult cut small wedges on one end of the other two popsicle sticks. As shown in the video, this is easiest when the 2 sticks are aligned and marked with small cuts so the wedges will line up. Then, individually finish carving out the wedges at one end of each stick.
- Carefully slide one of the wedged sticks between the bottom two stacked popsicle sticks so only the bottommost stick is below the wedged stick. The wedged stick and stack of sticks should form an “X,” in other words, they should be perpendicular to each other.
- Next, attach the spoon to your other wedged stick using 2 rubber bands. The wedged end of the stick should be near the bottom of the spoon.
- Now, attach the two wedged popsicle sticks with your last rubber band. The wedged ends should be attached (the wedges are there to hold the rubber band in place better), and the stick with the spoon should lay across the top of the stacked sticks. The wedged stick that is in the stick stack should be near the bottom of the stack.
- Once you have attached the wedged sticks, position their joint (where the rubber band holds them together) as close to the stacked sticks as possible.
- Your catapult is ready for battle! Before experimenting with how far it can shoot, be sure to put your safety goggles on so no eyes are damaged in the name of science. To use the catapult, you will need to hold it in place in one hand, and with the other hand push the spoon down towards the floor and quickly release.
Catapults function using simple machines like a lever and fulcrum. In this case, the lever is the stick with the spoon attached, and the fulcrum is the stack of sticks. When you push the spoon down, the rubber band holding the wedged sticks together stretches and builds energy to snap the ends of the sticks back together when the spoon is released.
With the fulcrum (stacked sticks) very close to the ends of the wedged sticks, it takes a little more force to push the spoon down, but it gives a lot more power to the catapult. Play around with this by moving the fulcrum closer to and farther from the ends of the wedged sticks.