  In this paper, we strictly establish classical concepts and relations
according to a Dirac equation with scalar, vector and nonlinear potentials. To
calculate classical parameters for moving spinor, the local Lorentz
transformations for parameters are derived. The calculation shows that
different kinds of potentials result in different energy-speed relations, and
the energy-speed relations for these potentials are derived in detail. The
usual mass-energy relation $E = mc^2$ holds only for the linear spinor. The
energy-speed relations can be used as fingerprints to identify the interactive
potentials of a particle by elaborated experiments. The analysis and results of
this paper can also provide some natural explanations for the foundation of
quantum mechanics, and clarify some long-standing puzzles in the theory.
