Vortex Cannon – Kids Experiment

Using the power of air molecules, it’s possible to make a mini cannon capable of forcing out air at high pressures. Better yet, it’s possible to make this using common household objects! This is the Vortex Cannon experiment and is a bunch of fun to craft, use and learn about. All you need is the following:

You will need:

  • A balloon
  • A paper cup/small plastic bottle
  • Scissors
  • Duct tape/Elastic Band
  • An adult helper

Method:

  • Firstly, we need to get the right shape for your vortex cannon. Depending on whether you’re using a plastic cup or a plastic bottle, the instructions will change. If you’re using a plastic cup, simply take your scissors and cut a big hole out of the base of the cup. Make sure to not cut the whole bottom of the cup out. If you’re using a plastic bottle, instead you’ll need to use your scissors to cut the bottle in half. Discard the bottom half of the bottle and remove the lid if you haven’t already.
  • Next onto the balloon itself, this will act as the “air launcher”. Give the balloon a good stretch to loosen it up nicely. Once that’s done, tie the end of the balloon into a knot and prepare your scissors. Unlike with the bottle, this time we will be needing the bottom half of the balloon. Using your scissors, carefully cut the balloon in half and discard the bottom half.
  • Now let’s combine the two! Wrap the open-end of your balloon over the open-end of the cup/bottle. To keep the two parts secure and air-tight, use some duct tape or an elastic band to hold them together.
  • With all that done, you should have a fully working vortex cannon. Flick or pinch back the balloon on your cannon to give it a test and feel the air shoot out. Try blowing around some balls of paper or putting some fog inside the cannon so that you can see the effect of your creation. And of course, the bigger the vortex cannon, the greater the effect! There are a bunch of interesting examples of vortex cannons that can be found online.

The Science Bit:

As cool as the vortex cannon is, the fun doesn’t stop there! The science behind the vortex cannon experiment is interesting too. Essentially, the vortex cannon works by quickly applying force to the air molecules inside the cup or bottle. When the balloon surface snaps forward it collides directly with the air molecules inside the cup/bottle, pushing and accelerating them toward the hole at the end of the cup/bottle.

Because of the shape of the vortex cannon, the vortex itself comes out at a donut shape. The air in the donut rolls from the center to the edge and forms this shape because the air leaving the cup/bottle at the center of the hole is traveling faster than the air leaving around the edge of the hole. The air keeps its shape since the surrounding air is relatively slow moving and under higher pressure. We hope you all had fun making your very own vortex cannons!