Maxima and and minima of sound wave at given time represents air density (maxima represents compression) similarly. How does these curved lines over the water surface represent variation of air column about the surface? What does these intersection between these lines and bulge between them represent (Marked in picture below)? Why does a pressure antinode form on surface. How does such wave form?
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Qmechanic
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Sound waves contain two components: pressure and particle velocity. The energy of the eave constantly bounces back and forth between kinetic energy (velocity) and potential energy (pressure). Pressure and velocity are mostly 90 degrees out of phase, i.e. the velocity is zero where the pressure is max (or min) and the pressure is zero when the velocity is max (in either direction).
I think what the picture is supposed to be showing is a standing wave in a tube. The tube has an open end (top) and a closed end (bottom). It doesn't matter if the closed end is water, glass, or wood etc.
At the closed end the velocity is zero, since the air molecules can't move into the hard material. But that also creates a pressure maximum. At the open end it's the opposite: the pressure is zero since there are just a few molecules trying to compress the massive air volume outside, but there is plenty of velocity.
What that graph is showing appears to be the amplitude of the velocity along the tube: it's 0 at the closed end and max at the open end. The left picture shows half a wavelength and the right ones shows one and a half wavelength. That's typically for an open/closed combination: the length of the tube will be an odd multiple of have the wavelength of the standing wave.
If that's supposed to show how you make sound when you blow over a partially filled bottle, it's dead wrong. A bottle is a Helmholtz resonator and the frequency is determined by the acoustic spring (air in the body of the bottle) and the acoustic mass (air in the neck of the bottle).
Hilmar
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