Ceramics are mixtures of metallic and nonmetallic elements that withstand exteme thermal, chemical, and pressure environments. They have a high melting point, low corrosive action, and are chemically stable. Examples include rock, sand, clay, glass, brick, and porcelain.

Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.

Specific gravity is the ratio of the density of equal volumes of a substance and water and is measured by a hyrdometer.