physical quantity
quantitative characterization of an aspect of a physical entity, phenomenon, event, process, transformation, relation, system, or substance
energy
quantitative property of a physical system, recognizable in the performance of work and in the form of heat and light
acceleration
rate at which the magnitude and/or direction of velocity changes with time
frequency
number of occurrences or cycles per time
magnetic flux density
vector physical quantity describing production of a potential difference across a conductor when it is exposed to a varying magnetic field
relative atomic mass
dimensionless physical quantity: ratio of the average mass of atoms of an element to one unified atomic mass unit
heat
energy that is transferred from one body to another as the result of a difference in temperature
luminous flux
physical quantity
frame rate
number of frames rendered in one second
ullage
headspace of air in winemaking
altitude
height in relation to a certain reference point
decay width
measurement: used in nuclear and elementary particle physics
longitude of the ascending node
one of the orbital elements used to specify the orbit of an object in space
damping coefficient
inverse of the time constant of an exponentially decaying quantity
abundance
ecological quantity
thermal transmittance
rate of transfer of heat through matter, expressed as a U-value
Hamiltonian function
function of generalized positions and momenta in Hamiltonian mechanics
effective potential
mathematical expression
toughness
ability of a material to absorb energy and plastically deform without fracturing
magnitude
strength of seismic waves of an earthquake
heat capacity ratio
thermodynamic ratio of isobaric to isochoric specific heat capacities
reverberation time
time after which the sound energy density has fallen to a certain fraction of the initial value after the sound source has stopped emitting
shear stress
component of stress coplanar with a material cross section
amount-of-substance concentration
measure of the concentration of a solute in a solution, or of any chemical species, in terms of amount of substance in a given volume; most commonly expressed in units of moles of solute per litre of solution
information content
logarithmic quantity derived from the probability of a particular event
activity coefficient
value accounting for thermodynamic non-ideality of mixtures
cloud cover
fraction of the sky obscured by clouds when observed from a particular location
second moment of area
mathematical construct in engineering
bond order
formal measure of covalent bond strength: difference between the number of electron pairs in bonding and antibonding molecular orbitals
extent of reaction
difference between equilibrium and initial amount of a substance, divided by its stoichiometric number
spectral luminous efficiency
spectral sensitivity of human visual perception of brightness
molar attenuation coefficient
chemical quantity
work
energy transfer, or its amount (& direction), in a thermodynamic process due to macroscopic factors external to a thermodynamic system
volumetric heat capacity
thermal quality
Hatta number
dimensionless parameter that compares the rate of reaction in a liquid film to the rate of diffusion through the film
rolling resistance
force resisting the motion when a body (such as a ball, tire, or wheel) rolls on a surface
thermodynamic beta
reciprocal product of temperature with the Boltzmann constant, frequently used in exponentials in physics and chemistry and relating statistical mechanics to information theory
first moment of area
property of an object related to its resistance to shear stress
sound pressure
local pressure deviation from the ambient atmospheric pressure, caused by a sound wave
conserved quantity
(of a dynamical system) function of the dependent variables that is a constant (in other words, conserved) along each trajectory of the system
rest mass (invariant mass) or rest energy
body's intrinsic mass (or equivalent intrinsic energy), motion-independent (Lorentz invariant); equals total mass (or energy) when at rest
grade
tangent of the angle of a surface to the horizontal
magnetomotive force
a quantity representing the sum of magnetizing forces along a circuit
time constant
measure for the response of a dynamic system to a change of the system input
radiant exposure
incident radiant energy per area
geopotential
energy related to Earth's gravity
mass excess
difference between mass and mass number of a nuclide