What is the cause of the frictional force?

Before studying what is the main reason for the appearance of the friction force, it is necessary to understand what the friction force is in general.

Friction force
In physics, this concept is usually meant to mean the force that arises during the contact of two bodies, and which prevents their relative motion. It is worth noting one very important fact that the force is always directed opposite to the movement of bodies. As a result of friction, mechanical energy is replaced and converted into thermal energy. There are two types of friction:

Friction of movement.
Rest friction.
Motion friction is classified into rolling friction and sliding friction.
In order to calculate the friction force, there are certain formulas. Let’s consider in more detail. F tr = M * N

F is the friction force.

M is the coefficient of friction.

N is the reaction force of the support.

This value contributes to a decrease in body speed. An example of frictional force is when you take a run on an icy track. However, if the pavement was asphalt, sliding would not be observed.

Causes of friction force
The cause of the friction force is the presence of irregularities that are located on the surface of the contacting bodies. Even if, on occasion, the surface seems to be absolutely smooth, this does not mean that this is really so. If you look more closely and closely at this surface, you can find and notice that there are some roughness on it. It is these irregularities and roughness that interfere with each other, thereby engaging.