D-9 High-precision measurement of friction coefficent of a curling stone by digital image analysis

Abstract

Friction coefficient of a curling stone was measured with high-precision digital image analysis in order to obtain its relation to the translational velocity and speed of rotation. Movement of the curling stone near the house was recorded in the sequential images with the camera located on the ceiling. Calibrations to remove lens aberration were done prior to the experiment. The translational velocity was calculated using the positions of the stone derived from the sequential images. Then the friction coefficients were calculated from the decrease of the translational velocity, and analyzed with consideration of the relative velocity to ice including the effect of rotation. It was found that the friction coefficients become larger when the translational velocity is smaller with a maximum around 0.1 m/s.