A cylindrical column of air closed at one end and three different tuning forks were used in an experiment to measure the speed of sound in air - Leaving Cert Physics - Question 3 - 2006
Question 3
A cylindrical column of air closed at one end and three different tuning forks were used in an experiment to measure the speed of sound in air. A tuning fork of freq... show full transcript
Worked Solution & Example Answer:A cylindrical column of air closed at one end and three different tuning forks were used in an experiment to measure the speed of sound in air - Leaving Cert Physics - Question 3 - 2006
Step 1
how the length of the column of air was adjusted
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Answer
The length of the column of air was adjusted using an open pipe. The pipe was either raised or lowered while it was immersed in water, which allowed for the accurate measurement of the air column's length in resonance with the tuning fork.
Step 2
how the frequency of the column of air was measured
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The frequency of the column of air was measured by using a tuning fork. The frequency was read directly from the tuning fork, which is a known frequency (denoted as f) when placed over the column of air.
Step 3
how the diameter of the column of air was measured
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The diameter of the column of air was measured using internal pipe diameter measurements. This was conducted with a vernier or digital calipers to ensure precision. If a ruler was used instead, it would not be as accurate.
Step 4
How was it known that the air column was vibrating at its first harmonic?
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It was known that the air column was vibrating at its first harmonic when a loud sound or resonance was observed. This indicates that the conditions for the fundamental frequency were met.
Step 5
Using all of the data, calculate the speed of sound in air.
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The speed of sound in air can be calculated using the formula:
v=fλ
where ( \lambda = \frac{4}{1} \cdot (0.05, m) ) (since the diameter of the column affects wavelength). Substituting the values:
For ( vel_1 = 340(3) , m , s^{-1} ) at 512 Hz,
For ( vel_2 = 342(0) , m , s^{-1} ) at 480 Hz,
For ( vel_3 = 341(1) , m , s^{-1} ) at 426 Hz.
The average speed of sound vavg=341.13ms−1.
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