Some examples of periodic motion include a bouncing basketball, a swinging tire swing, a metronome or a planet in its orbit. Periodic motion is a physics term meaning the repetition of the same motion in the same amount of time.
The function is referred to as "periodic" because the intervals of time are called "periods;" in this type of motion, the periods are always the same for each particular movement as a period represents one movement. The number of periods in a given amount of time, such as a minute, is the frequency. Other examples of periodic motion include a ticking clock, a swinging ball on a chain or an ocean wave.