Measuring the Speed of Sound
Science: KS3, topic 3.3.13
Measuring the Speed of Sound - Experiment
Echoes can be used to measure the speed of sound.
Speed of sound - echo
- Two people stand a measured distance from a tall vertical wall.
- The distance should be about 100m.
Making a Sharp Sound
- The first person bangs two wooden blocks to make a sharp sound.
- The bang repeats every time the echo is heard.
Speed of sound - echo
- The second person starts counting from zero.
- The second person uses a stopwatch (timer).
- The stopwatch measures the time taken for a number of claps.
- The number of claps could be 50 or 100.
Sound Travel Time
- In the time between two successive claps, the sound travels to the wall and back.
Calculating Speed
- The speed of sound can be calculated from the following relationship:
- speed of sound = distance to wall × 2 × number of claps (N) ÷ time taken for N claps.
Test yourself on Measuring the Speed of Sound
In the echo experiment, if the distance to the wall is measured as larger than it really is, what happens to the calculated speed of sound?
A pupil stands 100 m from a wall and makes a loud sound. In the time between making the sound and hearing the echo, how far has the sound wave travelled in total?
Select the correct statement in each pair