The velocity of sound in air at a certain temperature is 350 ms−1. What will be the velocity of sound in helium at the same temperature? (γair=75)
[molecular mass of air = 29, molecular mass of helium = 4]
γ of helium =53=γHe
γ of air =75=γa
Va=√γaRTMaγHe=√γHeRTMHe
Dividing VaVHe=√γaγH.MHeMa=
⎷(75)(53).429=√2125×429=4.58×25×5.39=0.339VHe=Va0.339=3500.339=1032.45 ms−1
Ans: VHe=1032 m/s