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“Huh?” Jesse said. “What does that have to do with Rocco flying?” “It’s a physical property called ‘lift.’

Rocco’s wings, like a wing of an airplane, are designed to produce an upward force, called lift . See how the wing is slanted a little? Air mov- ing over the top of the wing flows faster than the air moving along the bottom of the wing. This means the air flowing over the top of the wing exerts less pres- sure than the air moving along the bottom. This creates an upward motion.” “Oh! I get it. Just like when you blew on the paper. The air you were blowing was moving faster than the air on the underside of the paper. There was less pressure on the top, so it is almost like the air on the bottom side of the paper pushed it up.” “Right! And that is how our friend Rocco here flies too.” Tyrell clapped his hands and Rocco lifted up off of Jesse’s shoulder and flew to his outstretched hand.

Bernoulli’s Principle Why does the air flowing over the

top of the slanted wing move faster? And how does that result in a lower pressure? The answer to these questions can be found in Bernoulli’s Principle. This says that as the speed of a fluid in motion (in this case, the air) increases, then the pressure in that fluid decreases. Ber- noulli’s principle was first discovered in the 1700s by a scientist in Switzerland named Daniel Bernoulli, who found that fluids in motion behave differently than fluids at rest.

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