Final answer:
The angle of friction is the angle made by the resultant vector of the normal and friction forces with the normal force, calculated as the arctangent of the coefficient of friction.
Step-by-step explanation:
The angle of friction is the angle made between the resultant vector of the normal force and the friction force, and the normal force alone. It's related to the coefficient of friction, which is a measure of the 'grippiness' or resistance between two surfaces in contact. If we have a coefficient of friction μ, the angle of friction (θ) can be calculated using the arctangent function:
Angle of friction (θ) = arctan(μ).
This angle helps determine the maximum angle before sliding begins on an inclined plane. Not to be confused with the contact angle, which relates to the tangents of liquid surfaces, the angle of friction is purely concerned with solid contact surfaces resisting motion.