Question

A 40-cm-long tube has a 40-cm-long insert that can be pulled in and out. A vibrating tuning fork is held next to the tube. As the insert is slowly pulled out, the sound from the tuning fork creates standing waves in the tube when the total length L is 42.5 cm , 59.2 cm , and 75.9 cm . (Figure 1)

Part A What is the frequency of the tuning fork? Assumevsound = 343 m/s Express your answer with the appropriate units.

Answer 1

The difference between each of the lengths is ∆L = 16.7 cm = 0.167 m

∆L = 75.9 cm − 59.2 cm = 16.7 cm

For an open-open tube, the fundamental wavelength is λ = 2∆L.

λ = 2 x 16.7 cm = 2 x 0.167 m = 0.334 m

The frequency is

f = v/λ

f = 343 m/s / 0.334 m

f = 1027 Hz

f = 1.027 KHz