Question

Two Examples of periodic Motion.

Answer 1

Hint:Periodic Motion is defined as the motion that is repeated after equal intervals of time. The same state of motion is repeated in specific intervals of time and the smallest interval will be the fundamental time period of the motion. The function of such a motion with respect to time is also a periodic function.

Complete Step-By-Step Answer:
Periodic Motion refers to those motions where the object repeats its motion after a certain period in time. This motion is described by parameters such as angular frequency and angular speed.
The least time after which the motion is repeated is referred to as Time period of the motion. The time period of the motion must be of some fixed value.
Examples of periodic motion are, a moving pendulum, a bouncing ball and even earth orbiting the Sun.

Now let us closely observe some of the periodic motion:

(i) A moving pendulum:
In a pendulum, we know that an object (bob) hangs vertically from the pendulum. This bob when released from its equilibrium starts a to and fro motion, and moves from extreme left to right.
It can be noted at the time after which the bob returns to the extreme right side is constant. The same is true for the extreme left side as well.
This time interval is known as the time period of the motion, and thus, this is an example of periodic motion.

(ii) Rotation of Earth about its axis:
Earth rotates around its axis, each rotation takes exactly\[24hours\]. Since, the motion is repeated after an exact time interval, it is also an example of periodic motion.

Note:It is to be kept in mind that Periodic motion and oscillatory motions must be confusing. It is important to note that all periodic motions are oscillatory however, the opposite is not true.
Oscillatory motion are referred to as those motion, in which the motion is referred after equal intervals of time (this is true for periodic motion). The time period of a periodic function is constant but can be changed by changing some factors like length of the pendulum.