friction force is the opposition to the motion of surfaces sliding across each other. what is one factor that affects the amount of friction?

Answer

Nature of the surfaces.

Explanation

Friction is the the force that opposes motion between two surfaces that are in relative motion. If two objects are in contact, one of it or both must be in motion for friction to exist.

Friction is affected by a number of factors.

One is the weight of the object. The more the weight of the object the higher the friction between it and the surface.

The other factor is the nature of the surfaces. Rough surfaces contribute to high friction while smooth surfaces reduces the friction between surfaces.