In a broad sense, what one attempts to do in rock engineering is to anticipate the motion of a proposed structure under a set of given conditions. The main design objective is to calculate displacements, and as a practical matter, to see whether the displacements are acceptable. The concepts of stress and strain arise in such inquiry and the additional equations needed to complete the system are equations that relate stress to strain. Differentiation twice with respect to time gives the interesting result that shows that the mass center moves as if it were a particle accelerating according to Newton's second law (resultant of external forces = time rate of change of linear momentum). Background literature includes texts that develop fundamentals of strength of materials, mechanics of materials, elasticity theory, and continuum mechanics. An annotated list of Rock properties data necessary for engineering design analysis may be found in numerous technical articles and handbooks.