This is one project that we had a ton of fun with, and it’s something you can do at home! Here is how we made our giant air cannon.
- Lets start with the materials you will need.
- Help from an adult. They will need something sharp.
- A trash can or bucket, and permission to ruin it
- Plastic sheet–such as a shower curtain, or plastic trash bags
- Tape or bungee cords, or both!
This can be done with almost any size of bucket or trashcan. Larger containers will be more dramatic. Once you have made your selection, make sure the plastic sheets that you have are big enough to cover the mouth of the vessel. then…
Start by cutting a hole in the bottom right in the center. The perfect size for this depends on the size of the trashcan, with smaller ones needing a smaller hole. You are aiming for something between 2 and 5 inches across. Get an adult to help with this. Depending on the material of the trashcan, a knife, box cutter, or sawzall might be the best tool for the job.
Take aim! The bottom of the trashcan is now the muzzle of your giant air cannon! Fire it at your friends, or knock over stacks of cups by lightly smacking the plastic covering the opening! Have fun!
One interesting thing: Sometimes when you fire at something and miss by a little bit, it will get pulled backwards! This is because the air that you shot out is interacting with the air molecules around the room. Below is a cool animation of how the air gets stirred up when it goes through the room
Animation of how the air molecules interact when a pocket of air is shot through stationary air. Credit: William J. Beaty
If you can get some fog into the can, it will blow smoke rings! Looking at the animation above, you can see why the smoke rings form. The smoke is in the swirling red bits above. In two dimensions, this just looks like a couple of circles, but that is the cross section of a ring. As the smoke passes through the air, it spreads out a bit, leading to the rings you see below!