Hooked on science: Air cannon

You can't see it, but it's all around us! I'm talking about air, and here's an experiment that will prove air takes up space.

Ingredients

• 2-liter bottle
• plastic bag
• rubber bands
• scissors

Instructions

STEP 1: Using the scissors, remove the bottom of the plastic bottle and leave the cap off.

STEP 2: Cut a square from the plastic bag big enough to cover the bottom of the bottle.

STEP 3: Using two rubber bands secure the piece of plastic to the bottom of the bottle.

STEP 4: Grab a friend and have them hold your air cannon a foot from your hand. Have your friend tap the center of the plastic using his finger.

Explanation

When you tap the plastic, the air molecules, which are taking up space inside the bottle, rush out hitting your hand.

Jason Lindsey is a science outreach educator at Discovery Playhouse. Check out his science blog "Hooked On Science" at jasonthescienceguysblog.blogspot.com/ for Web casts and tools you can use at home to get hooked on science. You can reach him at 573-334-0416; jlindsey@discoveryplayhouse.org or P.O. Box 1251 Cape Girardeau, Mo. 63702.