Describe How Sound Travels in Different Materials

Sound in air

Sound is a longitudinal wave. This means that its vibrations are in the same direction as its energy transfer.

To make a sound, an object needs to vibrate. This vibration is then passed from one place to another, as the sound wave forces air particles to collide with each other. 

Once the sound reaches a person, the ear vibrates too, and this is how the sound is heard. The speed of sound in air is 330 metres per second.

Sound in materials other than air

Let's now think about sound travelling in different materials.

You should know that particles in a solid are arranged very close together in a fixed pattern. This means that sound will travel faster in a solid than the air, as each particle takes less time to collide with the particles around it. 

The speed of sound in wood is 3,300 to 5,000 metres per second, depending on the type of wood.

So, for example, when you knock on a door, the sound will travel at least 10 times faster than the speed of sound in air!

Shown below is a table, showing the speed of sound in different materials:

As you can see, sound travels faster as the particles of the material get closer together. Sound is fastest through solids and slowest through gases.

Milk is slightly more dense than water, which is why the speed of sound in milk is slightly faster!

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