Mechanical wave
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- Please see the article wave for more information.
A mechanical wave is a wave that requires a medium through which to transmit energy. Sound waves, waves in a Slinky, and pressure waves are all examples of this. Sound waves need air molecules in order to exist; the Slinky waves need the Slinky, and the waves in the ocean need the water.
It follows, then, that mechanical waves cannot exist in a vacuum. This is the factor that distinguishes them from electromagnetic waves.
Mechanical waves are a local oscillation of material. Only the energy propagates; the oscillating material does not move far from its initial equilibrium position. Therefore, mechanical waves transport energy and not material.
A mechanical wave requires an initial energy input to be created. Once this initial energy is added, the wave will travel through the medium until all the energy has been transferred.
There are three types of mechanical waves. Transverse waves are waves that cause the medium to vibrate at a 90-degree angle to the direction of the wave. Two parts of the wave are the crest, and the trough. The crest is the highest point of the wave, and the trough is the lowest. The wavelength is the distance between each crest.
The next type is longitudinal waves. A longitudinal wave is much like a Slinky. When the particles the wave is traveling through are close together, it is called compression. When the particles it is traveling through are spread apart, it is called rarefaction.
The final type of wave is a surface wave. This type of wave travels along a surface that is between two mediums. An example of a surface wave would be waves in a pool, or in an ocean.
In all types of waves, the medium itself does not move. The wave travels by jumping from one particle of the medium to another.
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