Final answer:
A real-world example of a longitudinal wave is a sound wave, where the medium's particles vibrate in the direction of the wave's travel.
Step-by-step explanation:
An example of a longitudinal wave is a sound wave. In longitudinal waves, the particles of the medium through which the wave travels vibrate parallel to the direction of wave propagation. This is in contrast to transverse waves, where particle motion is perpendicular to the direction of wave travel. Wave characteristics such as wavelength, amplitude, period, frequency, and wave speed can be defined for longitudinal waves. Sound waves cause periodic variations in pressure as they move through mediums like air or water.