There are several common fluid properties used to describe fluid behavior. Density is the ratio of mass to volume of a substance. Specific volume is the volume occupied by a unit mass of substance. Specific weight is the force of gravity on a mass per unit volume. Specific gravity is the ratio of the density of a substance to the density of water. Specific gravity can also be defined as the ratio of the specific weight of a substance to the specific weight of water. The study of fluid statics often involves the change of fluid pressure due to the change in depth of the fluid. Fluid power uses a pressurized fluid in a sealed system to do work. Pascal’s Law, which states that pressure exerted by a confined fluid acts the same in all directions at right angles to the inside of the container wall. The study of fluid dynamics considers the flow of fluids. The main issues in fluid flow center on the velocity, pressure, and force necessary to cause the fluid to move.
By Gary Conner
By George N Bullen FSME