The coefficient of friction is a ratio of force. What force is it divided by?

The coefficient of friction is defined as the ratio of the force of friction between two bodies in contact to the normal force pressing them together. It is a dimensionless value that quantifies how much frictional force can be expected for a given normal force.

When determining the coefficient of friction, the frictional force is measured against the normal force acting perpendicular to the surfaces in contact. The normal force typically represents the weight of the object or the component of the forces that pushes these surfaces together. This ratio provides an understanding of how different materials will interact under various loads, which is critical for applications in manufacturing processes where understanding material behavior is key to optimizing performance and ensuring safety.

In this context, the inclusion of the normal force is essential because it directly affects the ability of the surfaces to build friction; without this force, the frictional interaction cannot be accurately assessed.