Some people hear the word cannon and automatically think about something violent, used in times of war or for celebrating a score at an athletic event. But this cannon is perfectly safe and can actually help you impress your friends while performing some amazing feats.

Question: How can you blow out a candle from across the room?

Science Online

The original air cannon was called the Air Blaster, made by the Wham-O toy company. It was introduced in 1965, and you can learn more about

Wham-O at their Web site. Follow the “About Us” link to read about the company's long history of innovative toys: www.wham-o.com.

Materials

• Clean 8-ounce yogurt container

• Adult helper

• Scissors or knife

• Medium balloon

• Rubber band

• Lit candle

Procedure

1. Ask your adult helper to cut a small hole in the bottom of the yogurt container. The hole should be approximately one-half inch in diameter.

2. Cut the mouth off the balloon and stretch it across the top opening of the yogurt container. Secure the balloon to the mouth of the container with the rubber band.

3. Tap on the balloon to produce a small burst of air out the hole in the bottom of the container.

4. Bring your air cannon near the candle and tap on the balloon until you can make the candle go out.

The Science Behind the Magic

When you tap on the balloon, you compress all the air in the container. As the volume of the air decreases, the pressure inside the container increases. All that air has to go somewhere, so it gets pushed out the hole in the bottom. As the air passes through the small hole, it picks up speed. The air comes out of the hole as a vortex, and it tends to keep its form and can travel surprising distances across a room.

Follow-Up

See how far you can move from the candle and still blow it out using your air cannon. Some cannons have been known to work from across an entire room. You can also set up paper cups on a table as targets and practice knocking them over. Be careful when using your air cannon around people or pets, however. An unexpected blast of air is not always a welcome surprise. Several versions of this air cannon are possible, including one you can purchase at many toy stores. But you can experiment with building larger versions yourself. You can try using a tin can, such as one that would hold soup, vegetables, or dog food. Or you could use a larger can, such as one that would hold canned tomatoes. If you really want to upgrade your air cannon, try making one out of a plastic bucket or garbage can. You will need to experiment with various materials in place of the balloon, but the larger you make your cannon, the farther its bursts of air will travel.