The diagram shows an investigation of the speed of sound in air. A pulse generator sends a short sound from a loudspeaker. A microphone and computer record ...
Question 1 Report
The diagram shows an investigation of the speed of sound in air. A pulse generator sends a short sound from a loudspeaker. A microphone and computer record the time delay before the sound arrives. The student moves the microphone further from the loudspeaker. Table 1 shows the results. The air temperature is kept constant.
| distance between loudspeaker and microphone / m | time delay / ms |
|---|---|
| 0.80 | 2.3 |
| 1.60 | 4.7 |
| 2.40 | 7.0 |
(a) State what is meant by time delay in this investigation. [1]
(b) Calculate the speed of sound using the result for 2.40 m. [3]
(c) Which variable must be kept constant so that a fair comparison is made between readings? [1]
(d) Explain why several distances, rather than one distance, are used. [2]
(e) Describe one way of improving the reliability of the time measurements. [2]
(f) State the energy transfer that takes place when the loudspeaker produces sound waves. [1]
Answer Details
(a) The time delay is the time from sound leaving the loudspeaker to reaching the microphone. [1]
(b) \[7.0\text{ ms}=0.0070\text{ s}\] \[v=\frac{d}{t}=\frac{2.40}{0.0070}=3.4\times10^2\text{ m/s}\] Accept \(343\text{ m/s}\). [3]
(c) Air temperature must be kept constant because it affects the speed of sound. [1]
(d) Several distances provide more data over a larger range. This allows anomalies to be identified and a mean or graph gradient to improve confidence in the result. [2]
(e) Repeat each timing measurement and calculate a mean. Electronic timing or data logging, and using a larger separation to give a longer delay, also improve reliability. [2]
(f) Electrical energy supplied to the loudspeaker is transferred to sound energy. [1]
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