Damped periodic motions used in the study of the drag coefficient

Abstract

The paper proposes a method and the related experimental setup for finding the drag coefficient for a body. The device consists in a pendulum materialized by a hinged rod initially in horizontal position. A spherical body immersed in a liquid is attached to the free end of the rod. The restoring force is created by a helical spring. The inertial characteristics of the pendulum can be changed using an additional mass. The differential equation characteristic to the motion of the pendulum is deduced and subsequently integrated numerically. The coincidence between experimental and theoretical data allow for viscosity evaluation.