Hydraulics and Fluid Mechanics

Vocabulary terms and definitions covering the fundamentals of pressure, buoyancy, Archimedes's principle, Pascal's Law, and hydraulic system components.

Pressure

The perpendicular force applied per unit area, quantified by the formula $P = \frac{F}{A}$ and measured in Pascals ($Pa$).

Liquid Pressure

The static pressure exerted by a liquid, which varies with depth and is expressed as $\rho g h$, where $\rho$ is the liquid density and $h$ is the depth from the liquid surface.

Atmospheric Pressure

The force per unit area exerted by the weight of Earth's air column above a surface, equal to about $101,325 \text{ Pascals (Pa)}$ or $1\text{ atm}$ at sea level.

Archimedes

A Greek mathematician born in $287 \text{ bc}$ who was the first to explain the principle of buoyancy.

Archimedes's Principle

A principle stating that an object immersed in a fluid receives an upward force equal to the weight of fluid it displaces.

Buoyancy

A net upward force created by fluid pressure; specifically, the difference between the greater water pressure pressing up on the bottom of an object and the lesser pressure pressing down on its top.

Pascal's Principle

The law stating that any change in pressure in one part of a fluid will be transmitted undiminished to all other parts of the fluid.

Hydraulic System

A technology that uses pressurized fluid, usually oil, to transfer energy, multiply force, and create mechanical motion based on Pascal's Law.

Pumps

Parts of a hydraulic system that move the hydraulic fluid from the tank through the system and build up pressure, including gear, vane, and piston types.

Cylinders

Components that turn pressure from hydraulic fluid into linear motion to move heavy objects by lifting, pushing, or pulling.

Valves

Mechanical parts that control where the hydraulic fluid will flow and how fast it will move within the system.

Actuators

Components that use the pressure in the system to move the machine equipment in the way it intends to be moved.