Viscous friction in standard rotational motion experiments

Abstract

The results of standard experiments demonstrating relationships between dynamic (torque, moment of inertia) and kinematic (angular acceleration) characteristics of rotational motion can provide information on viscous friction acting on the rotating system. The standard experiments presented in this paper were performed using a symmetrical horizontal rotator with changeable moment of inertia (a bar with a symmetrically positioned pair of disc weights) supplied with optical gate; the rotator was driven by a permanent external torque in a resisting ambient atmosphere. The data were processed using the least squares method. The sums of squares of the residuals from the best-fit line (chiSquare values) were used to find out which experiments were influenced by laminar airflows and when turbulent airflows could occur along part of the rotating bar. The proposed experiment can be included in laboratory experiments in bachelor study programmes at colleges and technical universities.