All phenomena in nature are characterized by motion. Mechanics deals
with the objective laws of mechanical motion of bodies, the simplest
form of motion. In the study of a science of nature, mathematics plays
an important rôle. Mechanics is the first science of nature which has
been expressed in terms of mathematics, by considering various
mathematical models, associated to phenomena of the surrounding nature.
Thus, its development was influenced by the use of a strong mathematical
tool. As it was already seen in the first two volumes of the present
book, its guideline is precisely the mathematical model of mechanics.
The classical models which we refer to are in fact models based on the
Newtonian model of mechanics, that is on its five principles, i.e.: the
inertia, the forces action, the action and reaction, the independence of
the forces action and the initial conditions principle, respectively.
Other models, e.g., the model of attraction forces between the particles
of a discrete mechanical system, are part of the considered Newtonian
model. Kepler's laws brilliantly verify this model in case of velocities
much smaller then the light velocity in vacuum.