Why does not the speed of sound depends on the pressure of the air?

1 Answer
Ultrilliam
Jun 7, 2018

See below

Explanation:

The original (Newton-Laplace) equation for the speed of sound in a fluid included a reference to the pressure of the fluid :

  • c = sqrt((gamma P)/rho) qquad square

Using the ideal gas law:

  • PV = n RT

And replacing with:

  • n = m/M, where M is molar mass

  • rho = m/V

  • implies n = (rho V)/M

Leads to:

PV= (rho V)/M RT, qquad P = (rho RT)/M

So:

square implies c = sqrt((gamma RT)/M)

An expression that references the temperature of the fluid.

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