The concepts and terms of mechanics

Mechanics can be understood in non-mathematical terms. Two important kinds of strength are ultimate or breaking strength, and yield strength--the stress which will cause a permanent deformity (e.g., bending a bone plate). Stress, like pressure, is measured in pounds per square inch. Strain is the percentage "gain in length." The strength of bone is roughly comparable to oak wood. With hyperemia and resorption of bone substance, this strength can fall drastically in a matter of weeks. Bone cement is well named; like cement it has almost no useful tensile strength. Its compressive strength is roughly comparable to bone. Doubling the depth of a beam quadruples its strength