  The purpose of the dynamics of moving systems is to search for the
mathematical model that describes the link between the resultant applied force,
that is the cause, and the speed of system that is the effect. This
mathematical link provides the law of motion and from Newton forward it has
been specified by an differential equation. Starting from the principles of the
Theory of Reference Frames it is possible to arrive at new interesting results
in the study and in the analysis of dynamical systems provided with linear
symmetry and central symmetry. Really the most interesting consequences are
relative to the behaviour of microphysical systems and elementary particles.
Some kinematic and dynamic physical parameters, valid for analysis of
mechanical systems, lose meaning in microphysical systems. For these systems it
is necessary to define therefore new parameters on the ground of the behaviour
of observable physical magnitudes. Surely the most important physical quantity,
defined in this paper and relative to elementary particles, is the
electrodynamic mass that is different from mass of mechanical systems. This
parameter allows to understand some features of the behaviour of elementary
particles in inertial and not inertial reference frames. In the last part of
the paper an important relation between time and mass is proved and new general
equations of space time are defined for any reference frame.
