1. Ratio of frictional force and the normal force between two forces
2. The coefficients of friction are dimensionless and must be determined experimentally. Their values depend on certain properties of both the body and surface
3. A dimensionless number that must be determined experimentally. The value depend on both the object and the surface.
4. The ratio of the frictional force to the normal force between two forces.

• Forces
• Mechanics