Speed of Sound in Different Media for Class 9

The speed of sound is the rate at which sound travels through a medium. In simple words, it tells us how fast sound moves from one place to another. Have you ever noticed that during a thunderstorm, you see lightning first and hear the sound of thunder after a few seconds? The reason is that light travels much faster than sound. So, the light from lightning reaches our eyes almost instantly, while the sound takes more time to reach our ears. This article is a perfect guide to understand what is the speed of sound and how it changes in different media.

Table of Contents

• Speed of Sound in Different Media
• How Was Avogadro’s Number Determined?

What is the Speed of Sound?

Sound travels through a medium at a finite speed. This means it takes some time to travel from one place to another.

Have you ever noticed that thunder is heard after lightning is seen?

This shows that sound travels slower than light. So, in simple words, the speed of sound is less than the speed of light. The speed of sound depends on the properties of the medium through which it travels.

Now, the obvious question is: does sound travel at the same speed everywhere? Let's discuss it in the next section.

Speed of Sound in Different Media

The speed of sound depends on the medium and its temperature. The speed of sound decreases when we go from solids to liquids and then to gases. Interestingly! As the temperature of a medium increases, the speed of sound also increases.

For example:

• Speed of sound in air at 0°C = 331 m/s
• Speed of sound in air at 22°C = 344 m/s

Now, let’s look at the speed of sound in different media.

Speed of sound in different media at 25 °C
State	Substance	Speed in m/s
Solids	Aluminium	6420
	Nickel	6040
	Steel	5960
	Iron	5950
	Brass	4700
	Glass (Flint)	3980
Liquids	Water (Sea)	1531
	Water (distilled)	1498
	Ethanol	1207
	Methanol	1103
Gases	Hydrogen	1284
	Helium	965
	Air	346
	Oxygen	316
	Sulphur dioxide	213

You do not need to memorise these values. They are given to help you understand how speed changes in different materials.

When an object moves faster than the speed of sound in air, it is said to travel at supersonic speed. Objects like bullets, jets, and some aircraft can move at such high speeds.

So far, in this article, we have seen that the speed of sound is the speed at which sound travels through a medium. It is slower than light and depends on the medium and temperature. We also understood that sound travels fastest in solids, slower in liquids, and slowest in gases.