Periodic and harmonic motion

Question

what is the difference between peiodic and harmonic motion? It seems that both of their motion are repect itself, back and forth with same distance and direction. ex : a basketball player dribbles a ball and a cart bounces back and forth.

Answer 1

Harmonic motion is a particular type of periodic motion.  The example of a basketball being dribbled is periodic but not harmonic.  You can think of harmonic motion as periodic motion that is represented by sine and cosine functions.

 

Examples of periodic motion would be a mass moving at the end of a spring or a pendulum swinging a small angles.  Both motions depend on the restoring force that is proportional to its distance or angle from equilibrium and can be modeled by the sine or cosine functions.