Physics KS3 / GCSE: Can a singer smash a glass using sound waves?

Jon Chase challenges young opera singers in Cardiff to smash glasses with their voices.

After measuring the natural frequency of the glass, can the singers match it with enough power to smash it?

The results are spectacular slowed down 300 times.

Smashing things with sound waves isn’t just for fun.

In medicine, sound waves can smash painful, hard growths inside the body, called kidney stones.

The sound waves that smashed the glasses travel through air.

But the kidney stone smashing waves travel through water.

To find out why, two of the singers join Jon by Cardiff Harbour for an experiment.

Does sound travel faster in water or air?

This clip is from the series Wave World.

Teacher Notes

Key Stage 3

Pupils will have learnt at KS2 that sound is caused by vibrations and will have explored how the pitch and volume of sounds can be changed in a variety of ways.

They will need to be introduced to the term ‘frequency’, measured in Hertz (Hz), as a measure of how fast the sound vibrates.

Teachers might then use an oscilloscope and a signal generator to illustrate this through sine waves, and pupils could investigate using different tuning forks to explore the relation between the frequency of vibrations and the pitch of the note.

Pupils could research other applications of ultrasound such as cleaning and physiotherapy.

Key Stage 4

This could be used to illustrate the idea of waves transferring energy and one beneficial use of wave motion (ultrasound) in medicine.

Students could then research other uses of ultrasound in medicine, or analyse data on the hearing ranges of different animals, such as whales and dolphins, and explain the differences.

Curriculum Notes

This clips is relevant for teaching Physics at KS3 or KS4 and National 4/5.

This appears in AQA, OCR, EDEXCEL, WJEC GCSE in England and Wales, CCEA GCSE in Northern Ireland and SQA National 5 in Scotland.