This book deals with large-scale mechanics of materials. Although matter is composed of minute discrete particles acting upon each other in some definite way, engineering applications typically deal with the gross influence of the presence of the material in some region of space that would contain an extremely large number of such particles. The effect of an individual particle is not detectable and experiments can be interpreted by a theory that ignores the existence of discrete particles and instead imagines matter to consist of a smooth distribution of material, infinitely divisible into smaller and smaller portions, each composed of smoothly distributed material. Such a hypothetical material is referred to as a continuous medium.