A relativistically covariant formalism describing the behavior of a continuous medium is presented. A method is developed for resolving covariant expressions into space and time components. One obtains by this method from a symmetric energy-momentum tensor, a scalar invariant energy density, a vector heat flux, and the stress tensor. The laws of thermodynamics appear as time components and the laws of dynamics as space components of the same relativistic equations. If the divergence of the energy-momentum tensor vanishes, then the first law of thermodynamics and Newton's second law of dynamics (including thermal effects) follow. Reversible processes are considered, and the second law of thermodynamics is formulated with the use of scalar invariant temperature and entropy.