Strength of Materials

1.2 CONTINUUM

Molecules within substances are in constant motion and collide with each other. The number of molecules involved in a substance is immense. In engineering problems, we are not interested in the motion of individual particles but in the overall or bulk property although the property arises from its molecular structure.

If the microscopic nature of matter is not directly considered but the properties of a substance are assumed to exist as a continuous distribution of mass, then this idealized substance is called a continuum. This hypothetical continuum concept emphasizes that the conditions at a point are the average of a very large number of molecules surrounding that point within a reasonable distance. Thus, in a continuum the gross ...