Newton’s formula for speed of sound in a gas
v = √(P/ρ)
The density of air at temperature 0°C and pressure 76 cm of mercury column is ρ = 1.293 kg/m³
So P = .76m*(13.6*10^3 kg/ m³)*(9.8 m/s²) = 101292.8
Hence P/ ρ = 78339.37
√(P/ρ) = 279.8917 m/s
The velocity of sound in air comes as 280 m/s.
But the measured value of speed of sound in air is 332 m/s
Laplace suggested a correction. With Laplace’s correction the formula is
v = √( γ P/ρ)
where γ = Cp/Cv (Cp and Cv are molar heat capacities at constant pressure and constant volume respectively)
With this new formula the value comes out to be 331.1723 closer to 332 m/s.
The apparent change in frequency of the wave due to motion of the source or the observer is called Doppler Effect.
Macn Number = µs/v
µs = speed of source creating the sound wave
v = velocity of sound wave