Question

Is Friction independent of the actual area of contact?

Answer 1

Friction

1. Friction is the force that tries to prevent one surface from moving across another.
2. It can work on any two-layer surface, such as two solid surfaces, two fluid layers, or two gaseous layers.
3. Walking, sliding, applying brakes to halt a moving car, writing on a notebook or blackboard, hammering a nail into a wall, and so on all require friction.
4. Friction is solely determined by the nature of the surfaces in contact and the body's weight.

Formula of friction

$f=\mu N[wheref=forceoffriction,\mu =coefficiedntoffriction,N=normalreaction]$

Proving that friction is independent of the area of contact

1. Assume there are three identical objects with the same mass of 10 kg but different shapes.
2. The first object is a cube, the second is a cone, and the third is a square plate (cuboid).
3. A spring balance connects each of them independently.
4. When the spring balance registers a reading of 20 N, each object is pushed one by one and begins to slide.
5. As a result, friction is constant in all circumstances, regardless of the contact area.
6. On an atomic scale, the contact area is a tiny percentage of the entire surface area.

Therefore yes, friction is independent of the actual area of contact.