What is an example of a longitudinal wave?

Sound waves are a prime example of longitudinal waves. In a longitudinal wave, the particle displacement occurs in the same direction as the wave's propagation. This means that as sound travels through a medium, such as air, it creates regions of compression and rarefaction. When a sound wave travels, air particles are pushed together in compressions and then pulled apart in rarefactions, thus transferring the energy of the sound through the medium.

Longitudinal waves can be contrasted with transverse waves, where the particle displacement is perpendicular to the direction of wave propagation, as is the case with light waves. Water waves exhibit characteristics of both longitudinal and transverse waves, leading to confusion in classification. Seismic waves, particularly P-waves, are another category of longitudinal waves; however, they are typically not the first example that comes to mind when asked for a common longitudinal wave. Sound waves, being prevalent and easily observable in everyday life, serve as the quintessential example.