From Wikipedia, the free encyclopedia.
A wave which needs a medium in order to propagate itself. Sound waves, waves in a Slinky, and water 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.
