The to and fro motion of a body from its rest position (or mean position) is called the oscillatory motion.
- The motion of a swing.
- The motion of the pendulum of a wall clock represent the oscillatory motion
In this motion , the bob of pendulum from its rest position moves to one side, comes back to the rest position , then moves to the other side and then again comes back to the rest position. This process is continuously repeated. Thus the oscillatory motion is repetitive after a regular interval of time.So such a motion is also the periodic motion.