Sound Speed
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At 20 °C, the speed of sound in air is about 343 metres per second, or one kilometre in 2.9 s or one mile in 4.7 s. It depends strongly on temperature as well as the medium through which a sound wave is propagating. At 0 °C, the speed of sound is about 331 m/s. The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior. In colloquial speech, speed of sound refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids. For example, while sound travels at 343 m/s in air, it travels at 1,481 m/s in water and at 5,120 m/s in iron.
