Try laying a postcard (or other rigid paper about the same size) bent lengthwise on a table. Now, try flipping the card over by blowing underneath it. Can you do it? C’mon, try blowing harder! Still can’t do it? That’s okay. Maybe there’s something important going on here!
No matter how hard you blow, the card will only cling to the table. Daniel Bernoulli (pronounced buhr-NOO-lee), a Swiss scientist who lived in the 1700s, discovered that when a gas moves quickly, it has lower pressure. By blowing underneath the card, the air below the card has lower pressure. That means that the higher pressure air on top of the card pushes down on the card more than the lower pressure air below pushes up, and the card clings to the table.
Yeah, Bernoulli was a pretty neat guy. Without him, we wouldn’t have airplanes! The wings of an airplane are curved on the top and flat on the bottom, so air travels faster on the top and creates lower pressure there. The higher pressure underneath the wings pushes up, letting the plane take off.
