VIBRATORY MOTION

Displace slightly the bob of a pendulum and then release it. Notice it: the bob moves back and forth with a vibratory motion. Similarly when a mass at the end of a spring is pulled down and then released, a vibratory of a clamped steel strip, are other examples of vibratory motion.
DEFINITION: -
"A body is said to execute vibratory motion if it repeats it's back and forth motion over the same path about its position of equilibrium".
A vibrating body oscillates, between extreme positions around an equilibrium position. Initially an external force is applied which displaces the body from the equilibrium position. The external force is then removed. Vibrations of the displaced body will ensue only when a restoring force acts on the body that would pull it towards its equilibrium position. But when the body reaches this position, it has towards its equilibrium position. But when the body reaches this positions, it has gained maximum velocity and by virtue of inertia, continues its motion. Thus the vibrating body overshoots the equilibrium position and is displaced in the opposite direction. The body moves back and forth until its energy is gradually dissipated in friction of various kinds.