MECHANICS IS THE ENGINEERING SCIENCE that deals with studying, defining, and mathematically quantifying “interactions” that take place among “things” in our universe. Our ability to perceive the physical manifestation of such interactions is embedded in the concept of a force, and the “things” that transmit forces among themselves are classified for purposes of analysis as being solid, fluid, or some combination of the two. The distinction between solid behavior and fluid behavior has to do with whether or not the “thing” involved has disturbance-response characteristics that are time rate dependent
