Question

An oscillatory motion is always periodic but a periodic motion is not always oscillatory. Give an example to support the statement.

Answer 1

Oscillatory motion:

1. The motion of an object in which the object moves to and fro or back and forth about its mean position (rest position) is called oscillatory motion.
2. The motion of a pendulum, the motion of a mass suspended by a string, and the motion of a swing are examples of oscillatory motion.

Periodic motion:

1. The motion which repeats itself at a fixed interval of time is called periodic motion.
2. The motion of a pendulum, the motion of the Earth about its axis or around the Sun, the Motion of a swing, the motion of the needle of a sewing machine, and the heartbeat of a normal person are examples of periodic motion.

An oscillatory motion is always periodic but a periodic motion is not always oscillatory because in oscillatory motion the body repeats its path in equal intervals of time but any body in periodic motion may not do to and fro motion about their mean position. Some examples are given below:

1. A pendulum repeats its path in every equal interval of time (time period) means it is both an oscillatory motion and a periodic motion.
2. Earth rotates on its axis in every equal interval of time but it does not do any kind of to and fro motion, which means it is a periodic motion but not an oscillatory motion.