Engineering Glossary

A measure of a material's stiffness, defined as the ratio of stress to strain in the linear elastic region. Denoted as E, it represents how much a material will deform under a given load.

A geometric property that describes how a cross-section's area is distributed about an axis. It determines a beam's resistance to bending and is denoted as I.

The displacement of a structural element from its original position under load. Maximum deflection is often limited by building codes to prevent serviceability issues.

The internal moment that causes a beam to bend when subjected to external loads. It represents the sum of moments about a point in the cross-section.

The normal stress induced in a beam due to bending. Calculated as σ = M·c/I, where M is bending moment, c is distance from neutral axis, and I is moment of inertia.

The reduction in voltage along a conductor due to its electrical resistance. Occurs as current flows through wires and is proportional to wire length and current magnitude.

A standardized wire gauge system used primarily in North America. Lower AWG numbers indicate thicker wires with lower resistance and higher current capacity.

The opposition to current flow in an electrical conductor, measured in ohms. Depends on material, length, cross-sectional area, and temperature.

An AC power distribution method using two wires (hot and neutral). Common in residential applications and smaller commercial loads.

An AC power distribution method using three conductors carrying currents 120° out of phase. More efficient for large loads and motors.

The ratio of the number of teeth on the driven gear to the driver gear. Determines the mechanical advantage and speed reduction in a gear train.

The ratio of output power to input power, expressed as a percentage. Accounts for energy losses due to friction, heat, and other factors.

Mass per unit volume of a material, typically expressed in kg/m³ or lb/ft³. A fundamental property used in weight calculations and fluid mechanics.

A dimensionless quantity that predicts flow patterns. Defined as Re = ρVD/μ, it indicates whether flow is laminar (Re < 2300), transitional, or turbulent (Re > 4000).

A dimensionless number used in the Darcy-Weisbach equation to calculate pressure drop. Depends on Reynolds number and pipe relative roughness.

An empirical equation for calculating pressure loss in pipes: ΔP = f·(L/D)·(ρV²/2). It accounts for pipe length, diameter, fluid properties, and flow regime.