Harmonic motion

Harmonic motion, vibrating or oscillating motion that repeats itself in equal time intervals, as in the motion of a swinging pendulum. This is known as simple harmonic motion (SHM). The central point about which oscillation takes place is called the equilibrium point, and the distance of the object from this point at a given time is called its displacement. Harmonic motion occurs only within certain limits. If either the pendulum or the spring is displaced too far, the motion will become irregular.