Friction force is the force that resists the relative motion between two surfaces that are in contact.
The formula for deriving friction force is F=uN, where F is the friction force, u is the coefficient of friction, and N is the normal force.
The coefficient of friction is a dimensionless constant that represents the amount of friction between two surfaces. It is dependent on the type of materials and the roughness of the surfaces.
The normal force, which is the force perpendicular to the surface of contact, affects the friction force because it determines the amount of force that is pressing the two surfaces together. The greater the normal force, the greater the friction force.
The coefficient of friction can be affected by factors such as the type of materials, the roughness or smoothness of the surfaces, the temperature, and the presence of any lubricants or fluids between the surfaces.