pendelnder

Pendelnder are devices consisting of a weight suspended from a pivot by a rod or string, capable of swinging back and forth under the influence of gravity. The motion is governed by restoring forces that, for small angular displacements, approximate simple harmonic motion. Pendelnder are used in a wide range of contexts, from clocks to scientific demonstrations.

In the ideal simple pendulum, the period T depends on the length L of the suspension and the acceleration due to gravity g, with T = 2π sqrt(L/g) under the small-angle approximation. Real pendelnder experience damping from air resistance and internal friction, which gradually reduces the amplitude. For larger angles or when the mass distribution is extended, the system behaves as a physical (compound) pendulum, described by T = 2π sqrt(I/(m g d)), where I is the moment of inertia about the pivot, m is the mass, and d is the distance from the pivot to the center of mass.

Pendelnder come in many forms, including single-weight pendelnder, pendulums with and without a flexible string, and torsion pendulums. They have played a central role in timekeeping, enabling accurate clocks since the 17th century. They also serve as important demonstrations in physics education for topics such as harmonic motion, damping, and resonance. Historical examples include Galileo’s early observations and Christiaan Huygens’ development of the pendulum clock, while the Foucault pendulum provides a simple demonstration of Earth’s rotation. Modern applications include laboratory experiments, gravimetry, and seismology, where pendulum principles help measure gravity, inertia, and ground motion.