What does the magnitude of the friction force depend on?

The friction force is determined by the following formula:

F friction = k * N,

where k is the coefficient of friction against the surface, a constant determined experimentally, which depends on the interacting substances and shapes of bodies;

N is the reaction force of the support, equal to the resultant of all forces along the Y-axis, in the simplest case, numerically equal to the force of gravity G = m * g.

Considering the formulas, we can conclude that the friction force depends on:

-from body weight;

-from the substances from which the interacting bodies are made;

-from the forms of bodies.