Blowing in the Wind

[15 Minutes]

How does a 747 lift itself off the ground? Or a Helicopter? Or a bird? Balloons fly because they are lighter than the air, but a plane is much, much heavier, often weighing several tons. The plane, the helicopter, and the bird use their wings and the rush of the wind to fly. Try this activity to show how the rushing of air can lift an object.

You'll need:

• 2 pieces of paper (8 1/2 by 11 size or similar) a paperback or hardcover book, at least an inch or more in thickness

What to do:

1. If possible, print out these directions. Read them through before you begin.
2. Gather everything you'll need and always remember science safety.
3. Place the 2 pieces of paper in the book so that there is at least an inch between them.
4. Hold the book in front of you so that the 2 pieces of paper hang down (vertically) and you are looking between them. At least 4 or more inches of paper should be hanging down from the book.
5. Blow air between the hanging papers. Watch how they move.
6. Increase and decrease the width between the pages and see how that changes the way they move.

Useful information:

The air of our atmosphere exerts pressure on everything around you, and on you. When you blow air through the straw your cheeks puff out because there is more air pressure inside your mouth than outside. When you inhale quickly your cheeks collapse inward because there is less air pressure inside you mouth than outside. Now when air moves across a surface it exerts less pressure than if the air was not moving. The greater the air speed the less the pressure. And air pressure can move an object. If an object has more air pressure on one side than the other it is pushed in the direction of less pressure. When you put your face into the wind, you feel it pushing you backward because there is less pressure on the back of your head. That is why the 2 pieces of paper move toward each other – because the flowing air creates less pressure in between the pages than the non-flowing air on the outside of the 2 pieces of paper. The lifting pressure may seem small when you see it in this activity. But on the special shape of a wing it is more than enough to lift a 747 with all its passengers safely into the air.