Air Vortex Cannon

What you need:

• A cardboard box

• Box cutter

• Duct tape

• Marker

• Cups

What you do:

1. Tape your cardboard box closed with duct tape on the long sides of the box.

2. Then, place the duct tape roll on one of the shorter sides. Trace a circle around the duct tape roll.

3. Cut out the circle.

4. Lay the cardboard box on one of the long sides. Place a few cups a few feet away from the air vortex cannon.

5. Push the two long sides of the cardboard box toward each other and watch the air vortex cannon knock over the cups.

Questions to ask:

1. What do you think would happen if the hole were a square or a triangle?

2. What do you think would happen if the hole were larger or smaller?

What's the science:

This activity uses fluid dynamics. When you hit the sides of the back of your cannon, it causes air to move, and as it travels from back to front, it creates a vortex when it hits the opening. Vortex is just a fancy word for “swirl”. A vortex is generated when you hit the cannon because the air exiting the box at the center of the hole we created is traveling faster than the air exiting at the edge of the hole. 

If you want to see your vortex, you can fill your box with theatrical smoke or incense and aim the vortex cannon at a light fixture to see it. Also, gently tapping the back of the cannon creates a slow-moving, easy-to-see vortex.