A race of sound

The idea

The speed of sound depends on the medium: it is fastest in solids, slower in liquids and slowest in gases.

Three lanes

A clap is made at the start of three equal lanes. The first lane is air, the second is seawater and the third is a steel bar.

In which lane do you think the sound reaches the end first?

• Steel
• Air
• Seawater

Run the race

Press Run the race. The speeds are the ones used in the book's examples.

Fast, slower, slowest

The speed of sound depends on the medium. It is highest in a solid, lower in a liquid and lowest in a gas. Sound travels about 4 to 5 times faster in water than in air, and typically 15 to 20 times faster in solids.

The speed of sound depends on the medium. It travels fastest in solids, slower in liquids and slowest in gases.

Notes

The speed of sound depends on the medium: fastest in solids, slower in liquids, slowest in gases.

Check yourself

In which kind of medium does sound travel fastest?

Which order lists the media from fastest sound to slowest sound?

About how many times faster does sound travel in water than in air?

Sound travels in steel at 5000 m s⁻¹ (as in Example 10.4). How far does it go in 2 seconds, in m?

Answer: 10000 m

Distance = speed × time = 5000 m s⁻¹ × 2 s = 10000 m.

• A liquid. Sound travels slower in liquids than in solids.
• A solid — correct. Yes!
• A gas. Sound travels slowest in gases.
• Gases, liquids, solids. This is the reverse order. Sound travels fastest in solids and slowest in gases.
• Liquids, solids, gases. Sound travels faster in solids than in liquids.
• Solids, liquids, gases — correct. Yes!
• About 4 to 5 times — correct. Yes!
• About 15 to 20 times. That is typically how much faster sound travels in solids than in air.
• About the same speed. Sound travels about 4 to 5 times faster in water than in air.