The Flow of Dry Water: Feynman's Physics Explained

Feynman Vol II10-11

Fluid dynamics studies liquids and gases in motion. The simplest case is an ideal fluid — incompressible and with no internal friction — playfully called 'dry water.' Its motion obeys Euler's equations, and for steady flow this gives Bernoulli's theorem, a statement of energy conservation along a streamline: where the fluid moves fast, the pressure is low, and where it moves slow, the pressure is high.

The big idea

In smooth flow, fast-moving fluid has low pressure (Bernoulli).

Think about it

How does air rushing faster over the top of a wing help create the lift that holds up an airplane?

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