A further analysis of the energy-momentum for a system of point particles and for a perfect fluid in finite volume

A simple analysis of the total energy-momentum of a system of non-interacting point particles shows that it represents a well defined 4-vector. A generalization for interacting charged particles including the self-forces is developed. A comparison between a system of point particles in an infinite volume and the perfect fluid in a finite volume is done. The finite volume case is analyzed in order to define an energy-momentum depending on the notion of instantaneity for a perfect fluid. The relativistic transformations of thermodynamic quantities are defined in a covariant form leading to a redefined relativistic Thermodynamics.