CAIE IGCSE Physics: Measuring the Speed of Sound Question Bank

Practise planning a distance-and-time experiment for sound speed, including apparatus, timing method and calculation.

Exam points

describe an echo or direct-timing method with a measured distance and a stopwatch
account for the out-and-back echo distance before using v = s/t to find sound speed
suggest repeats or a longer distance to reduce timing uncertainty in the measurement

[Maximum number: 4]

Describe an experiment to determine the speed of sound in air.
State the apparatus required, the measurements taken and how to calculate the speed of sound in air from the measurements.

You may draw a labelled diagram as part of your answer.

echo method (outside):

1 method of producing short, loud sound (e.g. clap / shout / cry out / bang 2 pieces of wood together)

2 measuring tape or trundle wheel, stopwatch and wall

3 (person) starts stopwatch when clap etc heard and stops it when echo heard

4 speed $=2 \times$ measured distance ÷ time

B4

OR

direct method outside:

1 method of producing short, loud sound (e.g. fire gun)

2 measuring tape or trundle wheel, stopwatch

3 (student at one end) starts stopwatch when smoke seen from gun and stops it when sound heard

4 speed = distance ÷ time

B4

OR

direct method (using digital):

1 method of producing short sound e.g. clap or hammer striking block

2 measuring tape or metre ruler, digital timer and microphones

3 digital timer starts when sound reaches first microphone and stops when sound reaches second microphone. Time difference is recorded on digital timer owtte

4 speed = distance ÷ time for direct method

B4

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3.4.6—Method involving a measurement of question 1