Measuring the speed of sound in air and solids
Lesson details
Learning outcome
I can describe how to measure the speed of sound in air and in a solid metal rod.
Key learning points
- The speed of sound in air is about 340 m/s.
- The speed of sound in air can be measured using an echo method and using speed = distance/time.
- The speed of sound in a metal rod can be found by measuring the length and the frequency produced when struck.
- A result is accurate if it is close to the true value.
- A result can be considered accurate if it is repeatable, reproducible and if systematic errors have been checked for.
Keywords
Synchronisation - Synchronisation is the process of ensuring two (or more) things happen at the same time.
Period - The period of a wave is the time taken for one oscillation.
Wavelength - The wavelength of a wave is the distance a wave travels during one period.
Accurate - A result is accurate if it is close to the true value.
Systematic error - A systematic error affects all results by the same amount.
Common misconception
If measurements are repeatable (or precise) then they will also be accurate.
Repeatable (or precise) measurements may involve a systematic error making them inaccurate.
Teacher tip
A teacher should be able perform the demonstration of the metal rod experiment quite easily. There are many free apps that can be downloaded onto a mobile phone that will measure the frequency, make sure you have tested one out before the lesson.
Content guidance
Risk assessment required - equipment
Supervision
Adult supervision required
Licence
except where otherwise stated. See Oak's terms & conditions (Collection 2).Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What is an echo?
Q2.The material or substance that a wave is travelling through is called the wave .
Q3.A wave has a frequency of 2 Hz and a wavelength of 10 m. What is the wave speed?
Q4.The time taken for one oscillation is called the of a wave.
Q5.Which one of these does not describe the wavelength of a wave?
Q6.Which word means a result is close to the true value?
Assessment exit quiz
6 Questions
Q1.Give the missing number in the following sentence. The accepted value for the speed of sound in air is m/s.
Q2.Which two of the below would allow a result to be considered accurate?
Q3.Starting with the measurement of distance, put the steps for the echo method of measuring the speed of sound into the correct order.
Q4.Andeep and Sofia are 100 m from a wall. Andeep makes a sound, Sofia measures the time for the echo to return as 0.64 s. Their result for the speed of sound, to 2 significant figures, is m/s.
Q5.Starting with the measurement of the rod length, put the steps for the method of measuring the speed of sound in a metal rod into the correct order.
Q6.Alex and Jun suspend a 1.20 m long metal rod on elastic bands. Jun strikes the rod and Alex uses a phone app to find the frequency of the sound: 2675 Hz. The speed of sound in the rod is m/s.
To help you plan your 10 combined science lesson on: Measuring the speed of sound in air and solids, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 10 combined science lesson on: Measuring the speed of sound in air and solids, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 4 combined science lessons from the Measuring waves unit, dive into the full secondary combined science curriculum, or learn more about lesson planning.