Question

What is the difference between the periodic motion and oscillatary motion?

Answer 1

Periodic motion is that motion which repeats itself after equal intervals of time. The interval of time is called the time period of periodic motion. Example: (i) motion of planets around the sun (ii) motion of the pendulum of a wall clock (iii) motion of the hands of a clock etc.

If a body is moving back and forth repeatedly about a mean position, it is said to possess oscillatory or vibratory motion. Example: (i) motion of the pendulum of a clock (ii) vibrations of the string of a sitar etc.An oscillatory motion is always periodic. A periodic motion may or may not be oscillatory. For example, the motion of planets around the Sun is always periodic but not oscillatory. The motion of the pendulum of a clock is periodic as well as oscillatory.