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Build a tool to demonstrate that air has volume, takes up space and can apply force to solid objects.
What You Need:
- Plastic Water or Bottle, 20 oz (cap removed)
- Duct Tape or Electrical Tape
- Paper Confetti
To Do and Observe:
1. Cut the bottom off the soda bottle.2. Cut the neck off the balloon and stretch it around the bottom of the bottle, leaving it lose enough that you can pull at the center of the balloon a bit.3. Tape the edge of the balloon in place around the bottom of the bottle.4. From about 6 inches away, aim the open end of the bottle at the confetti.Pull back the center of the balloon with your finger and release. What happens?
What's Going On:
When you pull the balloon back and release it, the balloon will push the air inside the bottle out through the other end. The air forced out the opening travels through the outside air with enough force to move objects. This activity demonstrates the fact that air has volume and occupies space. After you release the balloon, it snaps back into the interior of the bottle and the space inside the bottle gets smaller. This forces some of the air out of the hole. Another name for the air cannon is the “Vortex Generator.” The air that shoots out of the cannon is invisible to us, but actually looks like a swirling doughnut called a “vortex.” The air looks like a vortex because the air at the center of the bottle’s hole is moving faster that then air around the sides if the hole. When you aim the air at a pan of water, you can sometimes see the vortex “doughnut” effect in the ripples of water. Air is made up of billions of molecules moving very quickly and colliding into each other and various objects in their path. When you aim the Air Cannon at something, the air molecules hit it. When the air molecules hit something, they transfer some of their energy to it, making it move.
Additional Materials: · A saucer or dish of ping-pong balls · Bubble-maker toys · Balloons · Pan of Water Here are some other things you might want to explore: · Can you bounce balloons or bubbles in the air with your air cannon? · What do you think will happen if you shoot your cannon at a dish of water? · From how far away do you think the air can move a ping-pong ball? · Get a friend – how far way do you think they can get and still feel the air form your cannon?