Sound Summary

Sounds are longitudinal vibrations travelling in solids, liquids or gases.

Sound cannot travel in a vacuum because there is nothing for the vibrations to pass through.

Sound travels fastest through things that have tightly packed atoms: solids.

The speed of sound is slower in liquids than solids, and slowest in gases.

The speed of sound in air is around 340 m/s, in water about 1500 m/s and in solids around 5000 m/s.

Lightning causes thunder. The delay between them happens because the speed of light is nearly 1,000,000× that of sound in air.

Ultrasound

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