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Speed of Sound |
The speed of a sound wave varies greatly when propagated in different media, the propagation velocity depending on the elasticity (or compressibility), temperature and density of the medium in question.
See also: Acoustic Impedance, Particle Velocity, Refraction, Sound Propagation.
In air, for instance, temperature and atmospheric pressure are significant factors. At 0° Centigrade and 1.013 x 105 Newtons per square meter (normal atmospheric pressure), the speed of sound is 331.5 meters/sec, i.e. 1087 ft/sec or 740 miles/hour. At 20°C (68°F) the speed is 1130 ft/sec or 344 m/sec. Propagation speeds for other media are given in the chart below. For each degree Centigrade increase in temperature, the speed of sound increases by 0.61 m/sec or 2.0 ft/sec.
See: Doppler Effect, Echolocation, Sonar, Sonic Boom, Subsonic, Supersonic, Supersonic Transport, Wavelength.
|
Substance |
Temperature (°C) |
Speed (m/sec) |
Speed (ft/sec) |
|
CO2 |
0 |
258 |
816 |
|
CO2 |
35 |
274 |
900 |
|
Air |
0 |
331.5 |
1,087 |
|
Air |
20 |
344 |
1,130 |
|
Water Vapor |
35 |
402 |
1,320 |
|
Helium |
20 |
927 |
3,040 |
|
Hydrogen |
0 |
1,270 |
4,165 |
|
Water |
15 |
1,437 |
4,714 |
|
Steel |
- |
5,000 |
16,400 |