The mass vibrates up and down from a low point to a high point. Particles in a medium vibrate like masses on springs when a wave passes
Waves can take many forms, but there are two fundamental types of waves: "longitudinal" and "transverse". Both of these wave types are traveling disturbances, but they are different because of the way that they travel. As a wave travels through a medium, the particles that make up the medium are disturbed from their resting, or "equilibrium" positions.
In a longitudinal wave, the particles are disturbed in a direction parallel to the direction that the wave propagates. A longitudinal wave consists of "compressions" and "rarefactions" where particles are bunched together and spread out, respectively.
In a transverse wave, the particles are disturbed in a direction perpendicular to the direction that the wave propagates. The transverse wave video clip below provides a dynamic visualization of this type of wave. After either type of wave passes through a medium, the particles return to their equilibrium positions. Thus, waves travel through a medium with no net displacement of the particles in the medium.
To learn more about Waves and Wave Motion, visit Visionlearning.