Periodic motion refers to motion that is repeated in equal intervals of time/15%3A_Waves_and_Vibrations/15.3%3A_Periodic_Motion). In other words, it is motion that occurs over and over again in a regular and repeating fashion. Some examples of periodic motion include a rocking chair, a bouncing ball, a vibrating tuning fork, a swing in motion, the Earth in its orbit around the Sun, and a water wave.
Key features of periodic motion include:
-
Period: The interval of time for a repetition, or cycle, of the motion is called a period. It is the duration of one cycle in a repeating event/15%3A_Waves_and_Vibrations/15.3%3A_Periodic_Motion). For example, the period of the Earths orbit is one year.
-
Frequency: The number of periods per unit time is called the frequency. It is the reciprocal of the period/15%3A_Waves_and_Vibrations/15.3%3A_Periodic_Motion). For example, the frequency of a tuning fork might be 1,000 cycles per second.
-
Amplitude: The maximum displacement of an object from its equilibrium position is called the amplitude.
Simple harmonic motion is a special case of periodic motion where the restoring force is directly proportional to the displacement/15%3A_Waves_and_Vibrations/15.3%3A_Periodic_Motion). Examples of simple harmonic motion include the oscillation of a spring and the motion of a simple pendulum/15%3A_Waves_and_Vibrations/15.3%3A_Periodic_Motion).
Periodic motion can be described mathematically using the period, frequency, and amplitude. The period of an objects motion is defined as the time for the object to complete one full cycle. The frequency is the number of cycles per unit time/15%3A_Waves_and_Vibrations/15.3%3A_Periodic_Motion). The amplitude is the maximum displacement of an object from its equilibrium position.
