Comparison of Two Experiments Based on a Physical and a Torsion Pendulum to Determine the Mass Moment of Inertia Including Measurement Uncertainties

To determine the mass-moment-of-inertia properties of devices under test with particularly small mass moments of inertia (some 10⁻⁴ kg m²), two measurement set-ups based on different measurement principles were developed. One set-up is based on a physical pendulum, the second set-up incorporates a torsion pendulum. Both measurement set-ups and their measurement principles are described in detail, including the chosen data acquisition and analysis. Measurement uncertainty estimations according to the Guide to the Expression of Uncertainty in Measurement (GUM) were carried out for both set-ups by applying Monte Carlo simulations. Both set-ups were compared using the same three devices under test. For each measurement result, the measurement uncertainties were estimated. The measurement results are compared in terms of consistency and the resulting measurement uncertainties. For the given devices under test, the torsion pendulum set-up gave results with smaller measurement uncertainties compared to the set-up incorporating a physical pendulum.