The coefficient of friction is defined as the ratio of the frictional force (Ff) to the normal force (Fn), expressed as u = Ff/Fn. To determine the frictional force, one must either be given it or measure it, as it is not inherently known. The discussion highlights the need to clarify whether the friction is kinetic or static and whether the surface is horizontal, as these factors influence the calculation. The equation Ff = umg is mentioned, indicating that the normal force (Fn) is equal to mg on a horizontal surface. Understanding these variables is crucial for accurately determining the coefficient of friction for a block.
