Which variables can be directly measured to determine the coefficient of friction?

To determine the coefficient of friction, the primary variables that need to be directly measured are the normal force and the friction force. The coefficient of friction is defined as the ratio of the friction force to the normal force acting on an object. Thus, measuring both of these quantities allows for the calculation of the coefficient:

[ \text{Coefficient of Friction} (\mu) = \frac{\text{Friction Force}}{\text{Normal Force}} ]

The incline angle may also be relevant as it affects the normal force calculation when an object is on a slope. Although the incline angle itself isn't directly used in the calculation of the coefficient of friction, it influences the distribution of forces acting on the object, which must be considered when determining the friction force and the normal force.

In contrast, measuring factors such as surface area does not directly affect the coefficient of friction in a fundamental manner, since friction is mostly dependent on the types of materials in contact and the forces acting on them rather than the area in contact. While load mass can indirectly impact friction by affecting the normal force, which is dependent on gravity, it is not as direct as measuring the normal force itself. Hence, the most pertinent and directly measurable variables involved in calculating the coefficient of