  From a rigorous historic analysis of 1686 I. Newton and 1905 A. Einstein
works where the last derived the universal mass-energy relationship, it is
concluded that rest mass measures potential energy. From the same formula used
to obtain that relation, it is derived the ratio Total Energy/Potential Energy
is equal to the gamma relativistic factor. It is derived a formula for the
variation of a body rest mass with its position in a gravity field, explaining
with it the behavior of an atomic clock. It is revised the bodies free fall in
a gravitational field, finding that a constant total mass is equal to the
gravitational mass, while the variable rest mass is equal to the inertial mass,
maintaining all an identical behavior independent of their masses. A revision
of the E\"otv\"os experiment concludes that it is unable to detect the found
difference between inertial and gravitational mass. Applying the extended 1905
relativistic dynamics to Mercury, its perihelion shift is determined; it is
concluded with the convenience to continue its development, what can imply a
revision of Physics since 1905 with important results in the unification of
natural forces and other open problems.
