Vibration

Vibration means quickly moving back and forth (or up and down) about a point of equilibrium.^[1] The vibration may be periodic (having a pattern) or random. Something that is vibrating may shake at the same time. If it vibrates in a regular way, it may produce a musical note because it can make the air vibrate. This vibration will send sound waves to the ear and to the brain.

In structural engineering including earthquake engineering, vibrations may be bad. They may cause the structure to fail.

The time it takes a vibrating object to go back and forth completely is the period. The number of back-and-forth movements in one second is its frequency, measured in Hertz (Hz). The farthest possible distance from the equilibrium point is the amplitude.

1. ↑ Tongue, Benson 2001. Principles of vibration. Oxford University Press. ISBN 0-195-142462