Sound speed in air follows molecular kinetic theory prediction

Evidence

Temperature. Lower temperature means the molecular messengers are moving more sluggishly, reducing the speed with which pressure fluctuations are propagated. Every gas atom or molecule has on average the same energy as its neighbors, independent of its mass. Energy is defined as E = 1/2 mv2, where m is the mass of the molecule, and υ is its velocity. Energy per molecule in a gas is proportional to temperature, expressed in kelvin, or K (room temperature is 295 K). Thus at 273 K, the freezing point of water, the speed of sound in any gas should be times as fast as it is at room temperature, 295 K. At 295 K, the speed of sound in air is 343 m/s; thus we predict it to be 343 × 0.965 = 331 m/s at 273K or 0°C. This is indeed the measured value. — Eric J. Heller, Why You Hear What You Hear- An…, 174

Categorization

• XREF: Ties kinetic theory of gases to empirical sound speed, connecting to the reader’s interest in mechanisms of sound propagation.