Question

Sound propagating through air at `30^@ C` passes through a vertical cold front into air that is `4^@`. If the sound has a frequency of `2500 Hz`, by what percentage does its wavelength change in crossing the boundary ?

Answer 1

Velocity of sound at `30^@ C = (331 + 0.60 xx 30) m//s = 349 m//s`
Wavelength of sound at `30^@ = ((349)/(2500)) m = 0.1396 m`
Velocity of sound at `4^@ C = (331 + 0.60 xx 4) m//s = 333.4 m//s`
Wavelength of sound at `4^@ C = ((333.4)/(2500)) m = 0.13336 m`
`%` age change in wavelength `= ((0.1396 m - 0.13336 m)/(0.1396 m)) 100 = 4.5%`.