Engineering Glossary

Direct definitions for the quantities used across EngineeringFormula's calculators - what each one means, which formulas use it, and which calculators solve for it.

Each entry here covers one physical quantity - velocity, force, stress, and the rest of the vocabulary that shows up across this site's calculators. A definition alone is rarely enough to actually use a quantity correctly, so every entry also includes the formulas that quantity appears in, a table of real-world reference values so a number has something to be compared against, and links to every calculator that solves for it.

These aren't restated dictionary definitions - each one is written and fact-checked against the same standard as this site's calculators (see Accuracy & Methodology), and every numeric reference value on a term's page is a verified figure, not a rounded guess. Several terms are genuinely easy to confuse with a similarly-named neighbor - velocity vs. speed, stress vs. pressure, momentum vs. kinetic energy - and each entry's FAQ section addresses that specific confusion directly rather than repeating the same generic question across every page.

Definition

A direct explanation of what the quantity means in engineering calculations.

Formula links

Where the symbol appears and which calculators solve for it.

Common confusion

Short FAQs for terms people mix up, like stress vs. pressure.

Velocity(v)

Velocity is the rate of change of position with respect to time, in a stated direction.

Force(F)

Force is a push or pull on an object, causing it to accelerate, deform, or change momentum.

Torque(T)

Torque is a rotational force - the product of a force and the radius at which it's applied.

Pressure(p)

Pressure is force distributed over an area - how much push, per unit of surface.

Density(ρ)

Density is mass per unit volume - how much a given volume of a substance weighs.

Reynolds Number(Re)

Reynolds number is a dimensionless ratio of inertial to viscous forces in a flowing fluid.

Momentum(p)

Linear momentum is the product of an object's mass and velocity - a measure of how hard it is to stop.

Stress(σ)

Stress is internal force per unit area within a material, resisting an applied load.

Strain(ε)

Engineering strain is the fractional change in a material's length under load - deformation relative to its original size.

Power(P)

Power is the rate at which work is done or energy is transferred, per unit time.