Why are sound waves called pressure waves?
1 Answer
Because they propagate through a material medium in form of alternate regions of COMPRESSION (high pressure) and RAREFACTION (low pressure) of the material composing the medium.
Explanation:
If you have a look at a loudspeaker or your eardrum you'll see this idea. The membrane of the loudspeaker initially at rest (1) rapidly moves in and out, (2) and (3), causing the air to be compressed rapidly:
When this compressed (high pressure) front reaches your eardrum it sets it in motion repeating exactly the original movement of the membrane of the loudspeaker.
You can produce this pressure fronts also in solids or liquids. In these the molecules are connected more firmly together (bonds) and the original perturbation, producing pressure fronts, propagates more rapidly!
hope it helps!
