What are mechanical waves? But first what are waves? Waves in physics mean an oscillation about a fixed axis or a point that is accompanied by a transfer of energy that travels through the medium such as space or mass.
A mechanical wave is a wave that is an oscillation of matter and is responsible for transfer of energy through a medium. The distance of the wave’s propagation is limited by the medium of transmission. In this case, the oscillating material moves about a fixed point and there is very little translational motion. One interesting property of mechanical waves is the way they are measured, given by displacement divided by wavelength. This dimensionless factor when it reaches 1, results in generation of harmonic effects; for example, waves break on the beach when this factor exceeds one, resulting in turbulence.
Types of mechanical waves
In a longitudinal wave, the displacement of the particle is parallel to the direction of the wave propagation. What you see in the picture is the wave front progressing forward and the particles compressing and expanding in the same direction. This kind of a wave is marked by periodic compression zones and rarefaction zones, where the medium expands.
The particles in the wave do not move along with the wave though, they simply oscillate back and forth about their own equilibrium. Sound waves in air, the primary waves of an earthquake are examples of longitudinal waves.
In Transverse Waves, the displacement of the particle is perpendicular to the direction of propagation of the wave. You can see in the picture how the just the up and down motion of the particles in the wave results in the movement of the waves sideways.
In transverse waves too, the particles do not move along with the wave. They just move up and down about their equilibrium positions. The ripples on the surface of the water, secondary waves of an earthquake and light too are all examples of transverse waves.
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