Speed of Sound Lab

In this lab we were given the assignment of measuring the speed of sound. To obtain better results, we were supplied with a long hollow tube made out of cardboard, a microphone and LoggerPro software.

In order to measure the speed of sound in an enclosed space, we figured out that we could use simple kinematics to find the speed of sound.
From the kinematic equations, we considered:

Δx = vt + at²

  

where we assumed zero acceleration (no external forces), and therefore yielding the formula;

 Δx = vt

We measured the long tube to be;

L= Δx = 2.63 ± .005 m

From the graphs we could determine the time it took for the sound to travel to the end of the tube, and back.

We ran a total of 5 trials:

v =  Δx/t,   Δx = 2.63 ± .005 m

t initial (s)	t final (s)	Speed of sound, vs (m/s)
0.00426±.0000005	0.01124±.0000005	376.8±.81
0.00024±.0000005	0.00736±.0000005	369.4±.70
0.00062±.0000005	0.00776±.0000005	368.3±.70
0.00078±.0000005	0.00814±.0000005	357.3±.68
0.00078±.0000005	0.00760±.0000005	385.6±.73

Av. Speed of Sound =  371.4 ± 0.34 m/s

In order to get satisfactory data, the sound emitted through the tube needs to be brief. Short timed sounds like a finger snap are the most efficient because the time is very short. The wave propagates fast leaving less room for resonance or other interfering phenomena. 

The speed of sound in air at room temperature ( T = 20°C) is given by:
v = 331 + 0.60(20) m/s = 343 m/s.

When compared the experimental and actual values of the speed of sound, the percent error came up to be:

% = 7.95 ± 0.095

The percentage of error came up to be very low, which demonstrates quite a satisfactory result. However, some sources of error should be included, such as the proximity between the snapping fingers and the hole, the variations in the 'room temperature', and also possible interference in the collecting device.