Sound Waves

Sound is a longitudinal compression-expansion wave in a gas. The wave speed is

$$c = ( \gamma R T_{abs} )^{1/2}$$ (2.11)

where $\gamma$ and $R$ are constants and $T_{abs}$ is the absolute temperature. The absolute temperature is measured in Kelvins and is numerically given by

$$T_{abs} = T_C + 273^{\circ}$$ (2.12)

where $T_C$ is the temperature in Celsius degrees. The angular frequency of sound waves is thus given by

$$\omega = ck = ( \gamma R T_{abs} )^{1/2} k .$$ (2.13)

The speed of sound in air at normal temperatures is about $340 \mbox{ m} \mbox{ s}^{-1}$.