Pendeltest

Pendeltest, or pendulum test, is a method that uses the motion of a pendulum to measure physical quantities, test instruments, or characterize dynamic behavior of systems. The approach is widely used in physics, engineering, metrology, and geosciences because a pendulum provides a well defined, repeatable motion that can be analyzed with relatively simple models.

The underlying principle relies on the simple pendulum, consisting of a mass m suspended from a light rod or string of length L and allowed to swing from a small angle. For small amplitudes, the period T is approximately T = 2π√(L/g), where g is the local gravitational acceleration. More generally, the motion follows a nonlinear equation involving gravity and the angle of swing, and damping or friction introduces exponential decay of amplitude. By recording the swing, one can extract the period, natural frequency, and damping characteristics, and from these infer parameters such as g, the effective stiffness, or the damping coefficient.

Typical procedure involves assembling a pendulum with a known length, ensuring a low-friction pivot, releasing from a controlled initial angle, and measuring the angular displacement over time with a protractor, optical sensor, or video analysis. Successive peak times yield the period; the envelope of the swing amplitude provides damping information. Data are fitted to the appropriate pendulum model to estimate quantities of interest and their uncertainties.

Applications include determining local gravity, calibrating accelerometers and other sensors, characterizing the damping properties of mechanical components or suspensions, and validating dynamic models in engineering tests. Limitations stem from the small-angle approximation, air resistance, pivot friction, measurement noise, and the accuracy of the length and angle measurements. Historical pendulum experiments also illustrate fundamental principles of motion and gravitation.