Speed of Sound in a Gas
Speed of Sound in a Gas
Sound travels through a gas at a speed set by its temperature and properties — faster in hot, light gases.
The speed is a = √(γ·R·T). where γ is the heat-capacity ratio, R the specific gas constant and T the absolute temperature.
Inputs
gamma := 1.4=1.4
R := 287 J/(kg·K)=287 m^2/K/s^2
T := 288 K=288 K
Apply the ideal-gas speed-of-sound formula.
a := sqrt(gamma·R·T)=340.17 m/s
Results
Air at 15 °C carries sound at about 340 m/s. The speed rises with the square root of temperature, which is why it changes with altitude and weather.
Assumptions & limitations
- Ideal gas.
- Specific (per-mass) gas constant.
- Absolute temperature.