Speed of sound
I can measure the speed of sound waves in air using an echo method.
Speed of sound
I can measure the speed of sound waves in air using an echo method.
Lesson details
Key learning points
- The ‘speed of sound’ is the distance travelled by a sound wave pulse every second, measured in m/s.
- Sound wave speed depends on the medium: it is about 340 m/s in air, faster in liquids and faster still in solids.
- Sound waves can reflect from hard surfaces, travel back and be heard again (an echo).
- The speed of sound waves (or the distance they travel) can be calculated using the equation: speed = distance ÷ time.
- In an experiment, measuring longer distances and times means any errors are a smaller proportion of the measurements.
Common misconception
High pitched sounds (higher frequency sound waves) travel faster than low pitched sounds (lower frequency sound waves).
Take measurements for the speed of sound using a high-pitched blast of a whistle as well as the lower pitched sound of hitting pieces of wood together to show they are the same (within error).
Keywords
Speed - how fast something is moving, often measured in metres per second
Sound wave - a ‘pulse’ that travels through a material caused by forward and backward vibrations of particles
Medium - the material through which a wave travels
Frequency - the number of vibrations each second
Echolocation - a method of detecting distances to objects by making a sound and waiting for an echo to return
Equipment
a long tape measure or trundle wheel, timer, blocks of wood, whistle, a suitable outdoor space with a large distance (over 80 m) and a large, hard vertical wall
Content guidance
- Risk assessment required - equipment
Supervision
Adult supervision required
Licence
This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).
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