Daniel
Bernoulli, an eighteenth-century Swiss scientist, discovered that as the
velocity of a fluid increases, its pressure decreases.Bernoulli's principle can
be seen most easily through the use of a venturi tube. A venturi tube is simply
a tube which is narrower in the middle than it is at the ends. When the fluid
passing through the tube reaches the narrow part, it speeds up. According to
Bernoulli's principle, it then should exert less pressure.
As
the fluid passes over the central part of the tube more energy is used up as the
molecules accelerate. This leaves less energy to exert pressure, and the
pressure thus decreases. One way to describe this decrease in pressure is to
call it a differential pressure. This simply means that the pressure at one
point is different from the pressure at another point. For this reason, the
principle is sometimes called Bernoulli's Law of Pressure Differential. Since
Bernoulli’s principle applies to fluids and air being one of them, we can
explain the relationship between air velocity and pressure on the surfaces of an
airfoil.
Concerning
flight, Bernoulli's Principle has to do with the shape of an airplane's wing.
The bottom is flat, while the top is curved. Air travels across the top and
bottom in the same time, so air travels slower on the bottom (creating more
pressure) and faster on top (creating less pressure). This keeps the plane in
the air.
Jeff Danger, Science
Ranger
Cool Science Show For Kids
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