Your child will love playing with his food to make a working potato cannon. This explosive experiment demonstrates the basic principles of Boyle's Law, which states, "Under constant temperature, the volume of gas is inversely proportional to the total amount of pressure applied." In the case of the popping potato, the air in the pipe is the gas, lodged between two potato plugs. By shoving a broomstick into the pipe of the potato cannon, one plug pushes towards the other reducing the volume of gas, while increasing pressure. The pressure in the potato cannon is what sends the potato plug flying into the yard!
What You Need:
- Safety goggles for everyone involved
- 2 potatoes
- PVC pipe, 2–3 feet long with a 1-inch diameter
- Dowel or similar object, diameter narrower than the pipe
- Clear outdoor space
What You Do:
- Have your child lodge a potato into both ends of the pipe to plug it. She can set a potato on the ground and push the pipe down on it. Repeat for the opposite side.
- Tell everyone to put on their goggles!
- Have her hold the pipe in one hand and point it away from people, or anything fragile.
- Help her to position the broomstick at the end of the pipe closest to her, barely touching the potato plug.
- With your help, have her push the broomstick slowly through the pipe, pushing the first potato towards the second. Have her stop about a third of the way down and pull the broomstick out of the pipe.
- Get ready to shoot! Have her quickly ram the broomstick into the pipe. The potato at the end of the pipe will shoot out and should travel a great distance.
Helpful Tip: It's safer to perform this experiment outside in a wide, open space.