pendular

Pendular is an adjective relating to a pendulum or to pendulum‑like motion. The term derives from Latin pendulus, meaning hanging.

In physics, the most common reference is to the pendulum: a weight suspended from a pivot that can swing freely under gravity. In the ideal simple pendulum with small amplitudes, the period T depends on length l and gravity g as T = 2π√(l/g). Real pendulums exhibit damping from air resistance and pivot friction, causing amplitudes to decay over time. A related concept is the physical pendulum, where the entire body swings about a pivot; its period is T = 2π√(I/(m g d)), with I the moment of inertia about the pivot, m the mass, and d the distance from the pivot to the center of mass.

A well-known demonstration involving a pendulum is the Foucault pendulum, which shows the rotation of the plane of oscillation due to Earth’s rotation. The apparent precession depends on latitude: at the equator there is no precession, and at the poles the plane completes a full rotation each day.

Applications of pendulums include clocks and metronomes, where the periodic motion provides a time standard, and seismometers, which often use pendulum‑like elements to sense ground motion. In engineering and instrumentation, pendular mechanisms can be used to create stable, oscillatory references or to sense acceleration and orientation.

Beyond strict physics, pendular describes any motion or phenomenon characterized by back‑and‑forth swinging around a pivot or equilibrium, or oscillation between opposing states.