Inclined Plane - Friction Block

Purpose

To demonstrate that the coefficient of static friction is greater than the coefficient of sliding friction, and to determine the coefficient of static friction.

Equipment

Inclined plane with wood block, as photographed.

Images

c6-02

Description

Position the block on the incline and slowly increase the angle until the block begins to slide down the incline. Because the coefficient of sliding friction is greater than the coefficient of static friction, after the block starts sliding it will continue to slide. The coefficient of static friction is equal to the tangent of the angle at which the sliding commences.

References

V. E. Eaton, A Novel Method of Measuring the Coefficient of Dynamic Friction, AJP 4, 37-39, (1936). PHYSICS: Where's the Rub?, Discover Magazine, October 1995.