Use a simple machine to turn potential energy into kinetic energy.
A simple machine is a device that allows people to do more work with less energy. It specifically applies to making things move and works by using physics to its advantage.
When an object is moving, it has kinetic energy. For example, as a ball rolls down a hill, its kinetic energy increases. Potential energy is energy that results from your position. If you start from the bottom of the mountain and climb up, the potential energy at the bottom of the mountain will be zero, while it will be a lot at the top of the mountain. As you climb the mountain, you gain potential energy.
A catapult combines these two concepts to launch heavy objects long distances. The catapult you’ll be making today is much smaller than a real one but works exactly the same way.
Ready to make your own? Follow the written steps below!
Materials you will need:
- Popsicle sticks
- Rubber bands
- A bottle cap
- Glue (hot glue works best)
- Pompom balls
Directions:
Step 1: Glue the bottle cap onto one end of one of the popsicle sticks, leaving a bit of space above the cap. Let the glue dry.
Step 2: Stack 5 popsicle sticks on top of each other.
Step 3: Put the popsicle stick with the bottle cap on it perpendicularly – i.e., so it makes a cross – between first and second stick and another one between last and second to last. Leave ¾ of the stick on the other side of the stack.
Step 4: Tie rubber bands on both sides of the stack of sticks to hold it together.
Step 5: Tie the two perpendicular sticks together with a rubber band.
Step 6: Put the pompom ball into the bottle cap.
Step 7: Push down on the part of the stick behind the bottle cap and release. Watch the pompom ball fly!
The Science of Popsicle Stick Catapult
- When you push the stick with the ball down, you are putting potential energy into the ball.
- When you release the stick, the potential energy in the ball turns into kinetic energy.
- The ball doesn’t go forever because it eventually loses kinetic energy due to the force of gravity.