1. speed of sound
Wikipedia definition
2. Speed of soundThe speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the speed of sound is 343.2 metres per second (1,126 ft/s). This is 1,236 kilometres per hour (768 mph), or about one kilometer in three seconds or approximately one mile in five seconds. In fluid dynamics, the speed of sound in a fluid medium (gas or liquid) is used as a relative measure of speed itself.
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