  Most of the logical objections against the classical laws of motion, as they
are usually presented in textbooks, centre on the fact that defining force in
terms of mass and acceleration, the first two laws are mere assertions of
concepts to be introduced in the theory; conversely, the third law expresses
the experimental fact that the ratio of masses is inversely proportional to the
ratio of accelerations, but it is known to fail when the interacting bodies are
rapidly accelerated or far apart, leading to objections at the research level,
particularly when electromagnetic phenomena is present. Following a
specification of the coordinate system with respect to which velocities and
accelerations are to be measured, relative to a fixed spacetime point, this
contribution argues that the limitation of the third law is removed; as a
consequence, Energy and Momentum relations are given an alternative
formulation, extending their fundamental aspects and terms to the relativistic
level. Most important, the presented alternative relations seem to preserve
exactly the same form of the concepts as originally used by Newton in the
Principia.
