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Have you ever watched a swing go back and forth at the park, or a washing machine spin its drum? These are both examples of periodic motion, a fundamental concept in physics.
Periodic Motion Definition
Periodic motion is any movement that repeats itself at regular intervals of time. The time taken to complete one full cycle of the motion is called the period.
Periodic Motion Example
 The swinging of a pendulum – A pendulum swinging back and forth is a classic example of periodic motion. The period of a pendulum depends on its length.
 The vibration of a mass on a spring – When a mass is attached to a spring and displaced from its equilibrium position, it will oscillate back and forth with a period that depends on the spring constant and mass.
 The motion of a rocking chair – A rocking chair moving back and forth is periodic motion. The period depends on the geometry of the chair.
Periodic Motion Diagram
Periodic Motion Formula
Period and Frequency (f = 1/T):

 This formula applies to all periodic motion.
 f represents the frequency, which is the number of cycles (repetitions) completed in one unit of time (usually seconds).
 T represents the period, which is the time it takes for one complete cycle of the motion.
Characteristics of Periodic Motion
Characteristics of Periodic Motion in Simple Words:
 Amplitude (A): The maximum distance an object moves from its resting position during one cycle of motion.
 Period (T): The time taken for the object to complete one full cycle of motion.
 Frequency (f): The number of cycles the object completes in a given time, usually measured in Hertz.
 Angular Frequency (ω): It is 2π times the frequency and helps describe the speed of the oscillation.
 Reciprocal Relationship: The frequency and period are reciprocals of each other, meaning f = 1/T and T = 1/f.
Types of Periodic Motion
 Simple Harmonic Motion (SHM): This is a special type of periodic motion where an object oscillates back and forth around a fixed point or equilibrium position. The force that pulls the object back towards the equilibrium is proportional to its displacement from that point. Examples include a mass on a spring and a pendulum swinging at small angles.
 Circular Motion: In circular motion, an object moves in a circular path around a fixed point. The distance from the object to the center (radius) remains constant, but its velocity and acceleration change continuously. Examples include the blades of a ceiling fan and a merrygoround.
 Oscillatory Motion: Oscillatory motion is a periodic motion where an object moves back and forth between two points. It can be linear, like a pendulum swinging, or rotational, like a mass on a spring. The key feature is the repeated backandforth movement between two positions.
 Wave Motion: Wave motion is a type of periodic motion that involves the propagation of disturbances through a medium. Examples include water waves, sound waves, and electromagnetic waves like light. The disturbance travels through the medium while the medium itself does not move.
Simple Harmonic Motion
Simple harmonic motion (SHM) is a type of periodic motion where an object oscillates back and forth around an equilibrium position, with the acceleration always directed towards that position and proportional to the displacement from it.
Simple Harmonic Motion Formula
 This is a special type of periodic motion where the restoring force is proportional to the displacement from equilibrium.
 A common formula used for SHM is:


 T = 2π√(m/k)
 T is the period (as defined above).
 m is the mass of the oscillating object.
 k is the spring constant (a measure of the stiffness of a spring) if a spring is involved in the motion.

Difference Between Periodic and NonPeriodic Motion
Characteristics  Periodic Motion  NonPeriodic Motion 

Definition  A motion that repeats itself at regular intervals  A motion that does not repeat itself at regular intervals 
Time  The occurrence of periodic motion is at regular intervals  The occurrence of nonperiodic motion is not at regular intervals 
Examples  Pendulum, clock hands, classes in schools  Vehicle on the road, soccer ball, swimming in a pool 
Repetition  The motion repeats itself after a fixed time interval  The motion does not repeat itself after a fixed time interval 
Position  After a certain period, the object returns to its original position  After a certain period, the object does not return to its original position 
FAQs on Periodic Motion
What is aperiodic motion?
Aperiodic motion is a type of motion that does not repeat itself at regular intervals. It is the opposite of periodic motion. Examples include a car driving on a road and a person walking randomly
What is periodic or nonperiodic motion?
Periodic motion is a type of movement that repeats itself at equal time intervals, like a pendulum swinging back and forth. Nonperiodic motion does not repeat itself regularly, such as a person walking randomly.
What is the difference between periodic motion and simple harmonic motion?
Simple harmonic motion is a distinct instance of periodic motion. A water wave, the swing and the tuning fork perform simple harmonic motions. On the other hand, the revolution of the Earth and the bouncing ball do not follow the principles of harmonic motion
What is periodic time of motion?
The periodic time is the time it takes for one complete cycle of a periodic motion to repeat itself. It is the time interval between two consecutive repetitions of the motion. The periodic time is measured in seconds.
What is the periodic motion?
Periodic motion is any movement that repeats itself at regular intervals of time. Examples include a swinging pendulum, a vibrating tuning fork, and the Earth revolving around the Sun. The time taken for one full cycle is called the period.
What is nonperiodic motion?
Nonperiodic motion is a type of motion that does not repeat itself at fixed time intervals. It is the opposite of periodic motion. Examples include a person walking randomly, a car driving on a road, and a bouncing ball slowing down due to friction.