Sound. The Wave Equation: Feynman's Physics Explained
Sound is a wave of pressure ripples traveling through a medium like air. We can derive the equation governing it — the wave equation — directly from Newton's laws applied to tiny volumes of air being compressed and expanded. Remarkably, the speed of sound depends not on the pressure or density but only on the temperature and the kind of molecules, coming out close to the average speed of the molecules themselves.
The big idea
Sound is a pressure wave, and Newton's laws predict its speed.
Think about it
Why does sound travel faster on a hot day than a cold one?
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