<P> Using the ideal gas law to replace p with nRT / V, and replacing ρ with nM / V, the equation for an ideal gas becomes </P> <Dl> <Dd> c i d e a l = γ ⋅ p ρ = γ ⋅ R ⋅ T M = γ ⋅ k ⋅ T m, (\ displaystyle c_ (\ mathrm (ideal)) = (\ sqrt (\ gamma \ cdot (p \ over \ rho))) = (\ sqrt (\ gamma \ cdot R \ cdot T \ over M)) = (\ sqrt (\ gamma \ cdot k \ cdot T \ over m)),) </Dd> </Dl> <Dd> c i d e a l = γ ⋅ p ρ = γ ⋅ R ⋅ T M = γ ⋅ k ⋅ T m, (\ displaystyle c_ (\ mathrm (ideal)) = (\ sqrt (\ gamma \ cdot (p \ over \ rho))) = (\ sqrt (\ gamma \ cdot R \ cdot T \ over M)) = (\ sqrt (\ gamma \ cdot k \ cdot T \ over m)),) </Dd> <Ul> <Li> c is the speed of sound in an ideal gas; </Li> <Li> R (approximately 8.314, 5 J mol K) is the molar gas constant (universal gas constant); </Li> <Li> k is the Boltzmann constant; </Li> <Li> γ (gamma) is the adiabatic index . At room temperature, where thermal energy is fully partitioned into rotation (rotations are fully excited) but quantum effects prevent excitation of vibrational modes, the value is 7 / 5 = 1.400 for diatomic molecules, according to kinetic theory . Gamma is actually experimentally measured over a range from 1.399, 1 to 1.403 at 0 ° C, for air . Gamma is exactly 5 / 3 = 1.6667 for monatomic gases such as noble gases; </Li> <Li> T is the absolute temperature; </Li> <Li> M is the molar mass of the gas . The mean molar mass for dry air is about 0.028, 964, 5 kg / mol; </Li> <Li> n is the number of moles; </Li> <Li> m is the mass of a single molecule . </Li> </Ul>

Speed of sound at sea level in feet per second