Question

Calculate the velocity of sound in air at NTP. The density of air at NTP is `(1.29g)/(L)`. Assume air to be diatomic with `gamma=1.4`. Also calculate the velocity of sound in air at `27^@C`.

Answer 1

Velocity of sound in air given by
`v=sqrt((gammaP)/(rho))=sqrt((1.4xx1.013xx10^5(N)/(m^2))/(1.29(kg)/(m^3)))=331.6(m)/(s)`
We can see that the velocity of sound is proportional to the square root of absolute temperature. Hence,
`(v_2)/(v_1)=sqrt((T_2)/(T_1))impliesv_2=v_1sqrt((T_2)/(T_1))=331.6sqrt((273+27)/(273))=347.6(m)/(s)`