Question

Refer the attached picture. ​

Answer 1

Newton assumed that when sound propagates through air, temperature remains constant (i.e. the process is isothermal).

So, bulk modulus of elasticity B = BT = p

(isothermal bulk modulus BT of a gas is equal to its pressure).

Therefore at NTP

p = 1.01 × 105 N/m2 and ρ = 1.3 kg/m3

= 279 m/s

The experimental value of v in air is 332 m/s at NTP. This discrepancy was removed by Laplace.