An open vertical tube is filled with water and a tuning fork vibrates over the top near the open end. As the water level is lowered in the tube, the first resonance is heard when the water level is at 31 cm from the top of the tube. What is the frequency of the tuning fork?

Question

An open vertical tube is filled with water and a tuning fork vibrates over the top near the open end. As the water level is lowered in the tube, the first resonance is heard when the water level is at 31 cm from the top of the tube. What is the frequency of the tuning fork?
The speed of sound in air is 343 m/s.
Answer in units of Hz

Damon · Answer

1/2 of the wave in the tube so wavelength = 2*31 = 62cm = .62 m distance = speed * T T = .62/343 so f = 1/T = 343/.62 = 553 Hz