What are the factors upon which friction does or does not depend?

Question

What are the factors upon which friction does or does not depend?

Answer 1

friction does not depend on speed and area of contact, but when we're talking about fluid friction or drag, it depends on both.

Answer 2

Let us define friction as the material resistance to applied force.  

What are the factors that create such resistance?  Above all else are the materials invovled.

Ice on ice has a very low "co-efficient of friction", while rubber on concrete has a much higher co-efficient.  The lowest known co-efficient among commonly encountered materials is Teflon.

Secondly, the weight (and angle) of bearing changes the friction between two objects (a heavier crate will resist a push more than a lighter one of similar materials).

Third is whether the object is standing still or already moving (a moving crate gives less resistance than a crate a rest)

Fourth is "surface area of contact".  A cabinet standing upright is easier to push than than the same cabinet laying on its back.

Fifth is temperature.  Try pushing ice-cold gum across a counter versus hot gum.

All of the above assumes that there is no additional materials (lubricants).  Additionally, a "polished" surface, will offer less resistance than an abrasive.

What factors does friction NOT depend on?  

Lateral forces.

Pushing an object harder will not change its resistance (tendency to remain at rest), but perhaps overcome the initial friction.  The amount of push you apply will not change the resistance unless you change the "at rest condition".

Hope this helps.