DIY Air Cannon

• Plastic or Styrofoam cups
• Scissors
• Balloon
• Various items to knock over

Step 1:  Gather materials.

Step 2:  Cut the neck off of the balloon and keep the large part.

Step 3:  Carefully cut a hole in the bottom of the cup about the size of a dime with your scissors. You may need an adult to help for this step.

Step 4:  Attach the cut balloon  to the mouth of the cup. Be sure to stretch it tightly and reinforce by wrapping a rubber band around the lip of the cup.

Step 5:  Pull back the balloon and let it go to force the air out of your cannon. You can also tap the balloon to fire the cannon.

Step 6:  You can hang a strip of toilet paper from a door frame and test how far back you can stand and still hit the toilet paper with the air cannon.

Although you can’t see it, your cup is filled with air. When you apply a force to the air molecules by pulling back the balloon and letting it snapback, the air molecules  are pushed toward the opening. This movement sets off a quick chain reaction of collisions with other air molecules and the sides of the cup. The only way for the air molecules to escape is through the opening at the bottom of the cup. The quick escape of these air molecules forms a stream of air that flows straight out of the cannon.

A meteorologist studies interactions between temperature, humidity, air pressure, precipitation and  vortices in the atmosphere. They develop an understanding of how vortices such as tornadoes, waterspouts and hurricanes form so they can predict the weather to keep people informed and safe.  They also study and learn about the polar vortex and how it affects the weather during winter.

Did you know that dolphins can create vortex rings to play with in the water by blowing air through their blowholes. The quick burst of air combined with the round shape of the blowhole create a vortex ring of bubbles.

To make this a true experiment, try changing a variable?

•  What might happen if you used a different sized cup?  Could you cut a 2 liter bottle to make a larger cannon?
• Could you try another stretchy material to take the place of the balloon?
• Does it change the experiment if you make the hole a different shape? What if you place it in a different spot?
• Experiment with your air cannon to see what changes allow you to shoot air the furthest.
• Have a target competition with a friend.