Speed of Sound Calculator
Works out the speed of sound in a gas from its temperature.
Speed of sound
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Time to travel 1 km — s
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The formula
a = √(γ R T ÷ M)
γ is the heat capacity ratio, R the gas constant, T the absolute temperature and M the molar mass. Pressure does not appear.
What to watch out for
For thunder, count the seconds after the flash. Every 3 s is about 1 km.
Frequently Asked Questions
What is the speed of sound at 20 °C?
343.2 m/s in dry air, and 331.3 m/s at 0 °C.
Why does helium raise your voice?
Sound moves faster in helium, at about 1,007 m/s at 20 °C, which shifts the resonances of the vocal tract upward.
How fast is sound in water or steel?
Roughly 1,480 m/s in water and 5,000–6,000 m/s in steel, depending on temperature and the type of steel.