Why are sound waves called mechanical waves?

- Hint: Study about waves and their classification on the basis of the direction of movement and on the basis of energy transmission through a medium. Also, understand about sound waves and list it according to the classification of sound.

Complete step-by-step solution -

A wave is a disturbance that travels from one place to another.
Waves can be classified on the basis of the direction of movement as:
Longitudinal wave- When particles of wave vibrate in a direction parallel to the direction of the wave then the wave is said to be longitudinal.
Transverse wave- When particles of a wave vibrate in a direction perpendicular to the direction of the wave then the wave is said to be transversal.
Waves can be classified on the basis of energy transmission through a medium as:
Electromagnetic wave- Waves that do not require medium to travel are known as an electromagnetic wave.
Mechanical wave- Waves that require a medium ( solid, liquid or gas) to travel are known as mechanical waves.
A sound wave is a wave in which particles vibrate in the direction parallel to the direction of the wave. So, sound waves are longitudinal. Also, it cannot travel through a vacuum and requires a medium (solid, liquid, or gas) to travel. Thus, a sound wave is called a mechanical wave.

Additional Information:
Sound is what we hear from our ear every day. We hear the different sounds because properties of sound like pitch, amplitude, and frequency vary according to the source of the sound. For example, males have a voice with more amplitude while females have a voice with a high pitch.
The speed of sound varies according to the medium in which it travels. It is maximum in solids while it is minimum in gases.

Note: Sounds wave does not have particles of the wave that vibrate in a direction perpendicular to the direction of the wave thus it is not called a transversal. And also, sound waves require medium while electromagnetic waves do not require medium to travel so they are not categorized under electromagnetic waves. To understand more about how sound is produced, observe a tuning fork, and do some experiments with it.