Periodic Motion - Definition, Examples, FAQs

Edited By Vishal kumar | Updated on Sep 24, 2024 06:26 PM IST

Periodic Motion Definition

Periodic motion is a motion that repeats itself after specific time intervals. Oscillation (or vibration) is back-and-forth periodic motion. The time T is the minimum time interval in which cyclic motion repeat itself, and the amplitude A of the cycle is the measure of the maximum displacement of the moving object from its mean position

JEE Main 2025: Physics Formula | Study Materials | High Scoring Topics | Preparation Guide

JEE Main 2025: Syllabus | Sample Papers | Mock Tests | PYQs | Study Plan 100 Days

NEET 2025: Syllabus | High Scoring Topics | PYQs

Periodic Motion - Definition, Examples, FAQs

Diagram of periodic motion of a spring mass system.	In practice, cyclic motion in a mechanical system will shut down due to the loss of energy.
The figure below shows examples of oscillating systems.

The time required to complete one cycle of the motion is the period T. Also called cyclic time

The inverse of the period is called frequency. f = 1 / T
The maximum displacement of the body from the equilibrium position is called amplitude A.

Also read -

What is meant by periodic motion?

Periodic motion is characterized by a continuous change with particular interval.

What is Periodic Motion or define periodic motion?

We often describe the movement of bodies by the way they move. If an object moves in such a way that it repeats its path at regular intervals after equal intervals of time, its motion is said to be cyclic OR periodic. Such motion is characterized by angular frequency, where the body moves at a certain angle with a certain speed called the angular speed given by, Here, Ω = 2 f, is the speed angle and f is the frequency. This motion can be represented by a sine wave, as shown below:

You have seen in schools that each lecture is given a fixed time interval. This fixed amount of time is known as the interval, but the teacher's daily arrival and departure is your teacher's periodic movement.

Also read :

JEE Main Highest Scoring Chapters & Topics

Just Study 40% Syllabus and Score upto 100%

Download E-book

Basic Terms Associated with SHM

Displacement is the distance of particle from its mean position at a given time. Measure in the mm, cm etc.
Amplitude is the maximum displacement of the oscillator on either side of its mean position.
Time period is the time taken by the oscillator to complete one oscillation.
Frequency is the number of oscillations completed by an oscillator in one second. It is denoted by v.
Phase φ is the angle whose sine or cosine at a given instant indicates the position and direction of motion of the oscillator. It is expressed in radians.
Angular Frequency ω is equal to the change of phase angle per unit time. It is expressed in rad per second.

Related Topics Link,

Some Examples of Periodic Motion

The revolution of the hands of a wall clock. The periodic time of an hour’s hand of a clock is 12 hrs, of a minute’s hand of a clock is 1 hour and of the second’s hand of a clock is 1 minute.
A pendulum hung from the wall, when pulled from its mean position to one side and loose free makes pendulum to make to and fro motion (oscillatory motion) is said to be periodic.
Oscillating balance wheel
rotating chair
Earth's rotation
Earth's rotation around its axis
Moon's rotation around Earth
Diapason
Blade of the propeller
Hand of the clock
Heart rate

Difference between Periodic and Non-Periodic Motion

Parameters	Periodic Motion	Non-Periodic Motion
Motion	Repeated motion	Non-repetitive motion
Time	The rate of periodic motion is totally dependent on the time interval.	The non-periodic motion doesn’t have such relevance.
Time period	It has a time period	It has a time of motion.
Type of motion	Vibratory or oscillatory motion.	Displacement of an object
Example	Movement of a girl sitting on a swing. The needle movement of the sewing machine runs at a constant speed. When the load attached to the spring is pulled once from its middle position and to the left, the spring begins to oscillate. Mercury in a U-tube Tubular movement. Movement of the mill in the motor during manual operation. The rotation of the moon around the sun.	Motion of a ball under the action of gravity and friction when throne from some distance Clouds gather in the sky and their movements. Vehicle movement at variable speed. Write on paper. A soccer player is running on the grass. A ball rolls on the ground. Perform any activity. Walking on the street. Play games.

NCERT Physics Notes:

Do you know?

• The earth's rotation around the sun is one year.

• The earth's rotation around its polar axis is one day.

• The period of revolution of the moon around the earth in 27.3 days.

• Oscillating motion can be expressed as sine or cosine waves or a combination thereof. It is due to the oscillating motion known as harmonic motion.

• The period of a simple pendulum has infinite length equal to the radius of the earth, i.e. 84.6 minutes.

• The length of time the pendulum clock in the elevator is in free fall under the influence of gravity is infinite.

Also check-

Frequently Asked Questions (FAQs)

1. What causes periodic motion?

According to Newton's first law, the law of inertia, if no force is applied to an object, the object moves in a straight line. A similar concept applies to objects that move periodically. A simple pendulum, when pulled out of its resting position (tension is a force), starts to move back and forth and tends to swing until we continue to apply force to the pendulum.

2. Why is simple harmonic motion periodic?

A harmonic motion can be represented by a sinusoidal wave motion. When the spring extends from the middle position, it swings back and forth around the middle position under the action of a restoring force that always points to the middle position. The size of the spring is proportional to the displacement of the object from the middle position at any position. This moment in time. There is no friction, and the movement remains periodic. In this case, the harmonic motion is periodic.

3. Can other actions be periodic?

All swing motions are called periodic motions, because each swing is completed in a fixed time interval. All oscillating motions are not periodic, just like the rotation of the earth is periodic, but not oscillating.

4. What are periodic and non-periodic changes?

The changes that occur regularly are called cyclical changes, such as the occurrence of day and night, and changes in the time of your school. Changes that do not occur periodically are called non-periodic changes, such as B. freezing into water.

5. Soldiers walking on the drawbridge are advised to leave the stairs. Why?

It is recommended that soldiers marching on the suspension bridge leave the steps, because in this case, the frequency of the marching steps corresponds to the natural frequency of the suspension bridge, and resonance occurs, which can greatly increase the vibration.

6. The vibrator of the harmonic oscillating single pendulum is made of ice. How will the rotational cycle change as the ice begins to melt?

The period of oscillation of a simple pendulum will remain constant until the position of the center of gravity of the pendulum remaining after the ice melts remains at the fixed position of the suspension. If the center of gravity of the iceberg is upward after melting, the effective length of the pendulum decreases and, therefore, the period of oscillation decreases. Likewise, if the center of gravity shifts downward, the time interval increases.