The Speed of Sound

 

The speed of sound is calculated using the formula:

 

velocity  =  frequency x wavelength

or

v  =  f x λ

 

Note: In physics the velocity is the speed of an object in a straight line.

 

Video of speed of sound experiment.

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Experimental Theory

Frequency

The frequency is engraved on the tuning fork. eg.

E 329.6 Hz
A 440 Hz
C 523.3 Hz

 

Wavelength

The resonance wavelength is one quarter of a wavelength.

Now since the air molecules vibrate most rapidly just over the cylinder a correction factor is included.

The correction factor is 0.3 times the diameter of the cylinder.

The wavelength is 4(l + 0.3d)

 

Speed of sound

The formula for the spped of sound is

velocity  =  frequency x wavelength

v  =  f x λ

Substituting  4(l + 0.3d) for wavelength(λ), the formula for the experiment becomes

v = f x 4( l+ 0.3d)

or

v = 4f( l+ 0.3d)

where v = velocity or speed of sound, f = frequency of the tuning fork, l = length of the vibrating cylinder from the top to the water level and d = diameter of the cylinder
 


Speed of sound calculator

The speed of sound calculator is designed for this experiment. Enter the numeric values for the

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  • Diameter of tube
  • Height of tube above water
  • Frequency of tuning fork
  • Diameter of the tube
  • Frequency of tuning fork
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Data Entry
Diameter of tube (cm)
Height of tube above water level (cm)
Frequency of tuning fork (Hertz)
Speed of sound (meters per second) Calculated

The speed of sound in dry air at 20°C (68°F) is 343.2 m/s

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