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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.