Velocity of sound

The speed of sound waves through a given medium. Usually quoted in describing properties of substances, such as Sodium.

More commonly the term refers to the speed of sound in air. In this case the physical properties of the air, its pressure and humidity for instance, affect the speed. However due to the complex way that all of these factors are interrelated, the speed in fact varies linerarly with temperature. An approximate speed can be calculated from:

v = 331 + (0.6 T), where T is the temperature in degrees Celsius

The speed of sound is typically measured given a "standard atmosphere". Under these conditions the speed of sound is approximately 343 m/s, or 750 miles/hour.

In solids the speed of sound is given by:

v = (E / ρ)^1/2, where E is Young's modulus and ρ is density.

Thus in steel the speed of sound is approximately 5100 m/s.