RI Sec 3 1998 EOY P2 Q10
In an experiment to determine the speed of sound in air, a student A with a gun stands at one end of an open field. Another student B with a stopwatch stands at the opposite end of the field 500 m away as show in the figure below.
When the gun is fired, it produces a bright flash and a loud bang.
Student B starts the stopwatch the instant he sees the flash of the gun and stops the stopwatch on hearing the bang. the experiment is performed three times and the values recorded by the stopwatch are 1.52 s, 1.48 s, and 1.59 s.
(a)
(i) Explain why the values recorded by the stopwatch are all different.
(ii) Calculate a value for the speed of sound in air.
(b) State how the values of time recorded would be affected if
(i) the gun produced a louder bang.
(ii) a wind blew in the direction from the stopwatch to the gun.
(c) Suggest one way to improve the accuracy of the experiment.
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Answer:
(a)
(i) Human reaction time.
(ii) Average value of recorded = (1.52 + 1.48 + 1.59) /3 ≈ 327 m/s
(b)
(i) There will be no change.
(ii) The time recorded will be longer.
(c) Repeat the experiment with a longer distance. A higher accuracy will be achieved because the human reaction time will be now a smaller percentage of the total time measured as compared to previously.
