Gone with the Wind

By:

Materials:

• Wind tubes
• Subway bags or umbrella bags

What to do:

Tie off one end of the Windtube. Ask students to estimate how many breaths it takes to blow up the 8 foot tube... 15?... 20?... 40? Ask a student to inflate the tube. Count the number of breaths required.  Then, show your students how, using Bernoulli’s Principle, you can inflate the tube with only one breath!

HOW: Have an assistant hold the closed end of the Windtube and extend it out horizontally. Hold the other end wide open. Keep your mouth about 10" away from the opening and blow a fast stream of air into the center of the tube for a few seconds. As soon as the tube is full, close it tightly with your hand and twist it tight. With a little practice, you’ll be an expert!* Once full, you can build structures or geometric shapes, toss in the air, play…

WHY: In 1738, Swiss physicist and mathematician, Daniel Bernoulli stated that as the velocity of a fluid (any gas or liquid that flows) increases, the pressure it exerts decreases. Fast moving air has a lower pressure than air that is not moving. The faster the air moves, the lower the pressure. Likewise, the fast stream of air moving from your mouth flowing into the Windtube has a lower pressure than the air outside the tube. Air from the room rushes into this low-pressure area within the Windtube and helps to fill the Windtube.*

*From Teacher Sourc