Systems of Units and Physical Quantities

Vocabulary flashcards covering the systems of units (CGS, FPS, MKS, SI), base units, and complimentary units including plane and solid angles.

Force

The physical quantity defined as $\text{mass} \times \text{acceleration}$, or formulated dimensionally as $\frac{m \times d}{t^2}$.

CGS System

A system of units where length is measured in centimeters ($\text{cm}$), mass in grams ($\text{gm}$), and time in seconds ($\text{sec}$).

FPS System

A system of units where length is measured in feet, mass in pounds, and time in seconds ($\text{sec}$).

MKS System

A system of units where length is measured in meters ($\text{m}$), mass in kilograms ($\text{kg}$), and time in seconds ($\text{sec}$).

SI Base Units

The seven fundamental units of the SI system: length ($\text{m}$), mass ($\text{kg}$), time ($\text{sec}$), thermodynamic temperature ($\text{K}$), electric current ($\text{A}$), amount of substance ($\text{mol}$), and luminous intensity (candela - $\text{cd}$).

Plane Angle ($d\theta$)

A complimentary SI quantity measured in radians ($\text{rad}$) and defined by the formula $d\theta = \frac{ds}{r}$.

Solid Angle ($d\Omega$)

A complimentary SI quantity measured in steradians ($\text{sr}$) and defined by the formula $d\Omega = \frac{dA}{r^2}$.

Radian ($\text{rad}$)

The complimentary unit for plane angles, related to degree measures such that $90^\circ = \frac{\pi}{2}\,\text{rad}$, $180^\circ = \pi\,\text{rad}$, and $360^\circ = 2\pi\,\text{rad}$.

Steradian ($\text{sr}$)

The complimentary unit used in the SI system to measure solid angles ($d\Omega$).