Answer: a) f = 15.95Hz effective length (L) = 50.91m
Explanation: The musical instrument is an open-closed tube thus it length (L) is related to the wavelength of sound passing through it is given below as
L = λ/4
Where λ= wavelength of sound wave
L = 18ft = 5.49m ( 1m = 3.28ft)
Hence, λ = 4L
λ = 5.49 * 4
λ = 21.95m
v = fλ where v = 350m/s, λ= 21.95m
f = v/λ = 350/ 21.95
f = 15.95Hz.
b) the actual fundamental frequency is 27.5 Hz
From v = fλ where v = 350m/s, we have the wavelength as
λ = v/f
λ = 350/ 27.5
λ = 12.73m
Assuming the instrument is an open-closed tube, then the length is given as
L = λ/4, but
λ = 12.73
L = 12.73 * 4
L = 50.91m