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Mechanical Waves

Definition: What are Mechanical Waves?

Mechanical waves are produced when particles vibrate in a medium in which the wave propagates. As a result, momentum and energy are exchanged among the particles and between the particles and the medium. Mechanical waves can propagate through solid, liquid, or gas. Examples of mechanical waves include ripples on the water surface (water waves), sound waves, and seismic waves.

Examples of Mechanical Waves

Types of Mechanical Waves

Mechanical Waves

Mechanical waves can be classified into two categories based on the motion of the particles – longitudinal and transverse. In longitudinal waves, the vibration or periodic disturbance takes place in the same direction as that of the propagation of the wave. In transverse waves, the vibration or periodic disturbance takes place in a direction perpendicular to that of the propagation of the wave.

Longitudinal Wave

When a longitudinal wave propagates, it compresses and rarifies the medium. The particles present in the medium moves back and forth along the direction of propagation of the wave. As a result, there are regions with high and low pressures. Examples of longitudinal waves include sound wave, ultrasound wave, and seismic P-wave. Waves traveling through the bulk of fluid are longitudinal waves.

Transverse Wave

Transverse waves can be represented by a sine or cosine function, called a wave function. The wave function determines the displacement of a particle from the axis of propagation at different times and distances from the origin. This displacement is proportional to the sine or cosine of the angle that the displacement vector makes with the axis. Examples of transverse waves include ripples on the water surface, vibrations on a guitar string, and seismic S-wave. Electromagnetic waves have transverse characteristics, but unlike other mechanical waves, they can propagate in a vacuum.


Q.1. What is the difference between mechanical waves and electromagnetic waves?

Ans. Mechanical waves require a medium to propagate. In contrast, electromechanical waves do not require a medium and can propagate in a vacuum.

Q.2. Are water waves mechanical waves?

Ans. Yes. Water waves are mechanical waves since the medium propagates along with water.

Q.3. Why do mechanical waves require a medium for transmission?

Ans. Mechanical waves require a medium for transmission because the particles need to move physically and touch each other in order to exchange energy and momentum.

Q.4. Are seismic waves mechanical waves?

Ans. Seismic waves are a type of mechanical wave because they can propagate through the surface of the earth.

Q.5. Do mechanical waves transfer energy?

Ans. Yes, mechanical waves transfer energy through the vibration of particles.

Article was last reviewed on Friday, March 6, 2020

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