# List of physical quantities

This is a list of physical quantities.

The first table lists the base quantities used in the International System of Units to define the physical dimension of physical quantities for dimensional analysis. The second table lists the derived physical quantities. Derived quantities can be mentioned in terms of the base quantities.

Note that neither the names nor the symbols used for the physical quantities are international standards. Some quantities are known as several different names such as the magnetic B-field which known as the magnetic flux density, the magnetic induction or simply as the magnetic field depending on the context. Similarly, surface tension can be denoted by either σ, γ or T. The table usually lists only one name and symbol.

The final column lists some special properties that some of the quantities have, such as their scaling behavior (i.e. whether the quantity is intensive or extensive), their transformation properties (i.e. whether the quantity is a scalar, vector or tensor) or whether the quantity is conserved.

Base quantity Symbol Description SI base unit Dimension Comments
Length l The one-dimensional extent of an object metre (m) L
Mass m A measure of resistance to acceleration kilogram (kg) M extensive, scalar
Time t The duration of an event second (s) T scalar
Electric current I Rate of flow of electrical charge per unit time ampere (A) I
Temperature T Average kinetic energy per degree of freedom of a system kelvin (K) Θ intensive, scalar
Amount of substance n

Number of particles compared to the number of atoms in 0.012 kg of 12C mole (mol) N extensive, scalar
Luminous intensity L Wavelength-weighted power of emitted light per unit solid angle candela (cd) J scalar
Derived quantity Symbol Description SI derived unit Dimension Comments
Absement A Measure of sustained displacement: the first integral of displacement m s L T vector
Absorbed dose rate Absorbed dose received per unit of time Gy s−1 L2 T−3
Acceleration a Change of the speed or velocity per unit time m s−2 L T−2 vector
Angular acceleration α Change in angular speed or velocity per unit time rad s−2 T−2
Angular momentum L Measure of the extent and direction an object rotates about a reference point kg m2 s−1 M L2 T−1 conserved quantity, pseudovector
Angular speed (or angular velocity) ω The angle incremented in a plane by a segment connecting an object and a reference point per unit time rad s−1 T−1 scalar or pseudovector
Area A Extent of a surface m2 L2 scalar
Area density ρA Mass per unit area kg m−2 M L−2
Capacitance C Stored charge per unit electric potential farad (F = A2 s4 kg−1 m−2) M−1 L−2 T4 I2 scalar
Catalytic activity Change in reaction rate due to presence of a catalyst katal (kat = mol s−1) T−1 N
Catalytic activity concentration Change in reaction rate due to presence of a catalyst per unit volume of the system kat m−3 L−3 T−1 N
Chemical potential μ Energy per unit change in amount of substance J mol−1 M L2 T−2 N−1 intensive
Crackle c Change of jounce per unit time: the fifth time derivative of position m s−5 L T−5 vector
Current density J Electric current per unit cross-section area A m−2 L−2 I vector
Dose equivalent H Received radiation adjusted for the effect on biological tissue sievert (Sv = m2 s−2) L2 T−2
Dynamic viscosity η Measure for the resistance of an incompressible fluid to stress Pa s M L−1 T−1
Electric charge Q The force per unit electric field strength coulomb (C = A s) T I extensive, conserved quantity
Electric charge density ρQ Electric charge per unit volume C m−3 L−3 T I intensive
Electric displacement D Strength of the electric displacement C m−2 L−2 T I vector field
Electric field strength E Strength of the electric field V m−1 M L T−3 I−1 vector field
Electrical conductance G Measure for how easily current flows through a material siemens (S = A2 s3 kg−1 m−2) M−1 L−2 T3 I2 scalar
Electrical conductivity σ Measure of a material's ability to conduct an electric current S m−1 M−1 L−3 T3 I2 scalar
Electric potential V Energy required to move a unit charge through an electric field from a reference point volt (V = kg m2 A−1 s−3) M L2 T−3 I−1 extensive, scalar
Electrical resistance R Electric potential per unit electric current ohm (Ω = kg m2 A−2 s−3) M L2 T−3 I−2 extensive, scalar, assumes linearity
Electrical resistivity ρ Bulk property equivalent of electrical resistance ohm metre (Ω⋅m = kg m3 A−2 s−3) M L3 T−3 I−2 intensive, scalar
Energy E Capacity of a body or system to do work joule (J = kg m2 s−2) M L2 T−2 extensive, scalar, conserved quantity
Energy density ρE Energy per unit volume J m−3 M L−1 T−2 intensive
Entropy S Logarithmic measure of the number of available states of a system J K−1 M L2 T−2 Θ−1 extensive, scalar
Force F Transfer of momentum per unit time newton (N = kg m s−2) M L T−2 extensive, vector
Frequency f Number of (periodic) occurrences per unit time hertz (Hz = s−1) T−1 scalar
Fuel efficiency Distance traveled per unit volume of fuel m m-3 ( = m/m3) L−2 scalar
Half-life t1/2 Time for a quantity to decay to half its initial value s T
Heat Q Thermal energy joule (J) M L2 T−2
Heat capacity Cp Energy per unit temperature change J K−1 M L2 T−2 Θ−1 extensive
Heat flux density ϕQ Heat flow per unit time per unit surface area W m−2 M T−3
Illuminance Ev Luminous flux per unit surface area lux (lx = cd sr m−2) L−2 J
Impedance Z Resistance to an alternating current of a given frequency, including effect on phase ohm (Ω = kg m2 A−2 s−3) M L2 T−3 I−2 complex scalar
Impulse J Transferred momentum newton second (N⋅s = kg m s−1) M L T−1 vector
Inductance L Magnetic flux generated per unit current through a circuit henry (H = kg m2 A−2 s−2) M L2 T−2 I−2 scalar
Irradiance E Electromagnetic radiation power per unit surface area W m−2 M T−3
Intensity I Power per unit cross sectional area W m−2 M T−3
Jerk j Change of acceleration per unit time: the third time derivative of position m s−3 L T−3 vector
Jounce (or snap) s Change of jerk per unit time: the fourth time derivative of position m s−4 L T−4 vector
Kinematic viscosity v Dynamic viscosity/density m2 s−1 L2 T−1 scalar
Linear density ρl Mass per unit length kg m−1 M L−1
Luminous flux (or luminous power) F Perceived power of a light source lumen (lm = cd sr) J
Mach number (or mach) M Ratio of flow velocity to the local speed of sound unitless 1
Magnetic field strength H Strength of a magnetic field A m−1 L−1 I vector field
Magnetic flux Φ Measure of magnetism, taking account of the strength and the extent of a magnetic field weber (Wb = kg m2 A−1 s−2) M L2 T−2 I−1 scalar
Magnetic flux density B Measure for the strength of the magnetic field tesla (T = kg A−1 s−2) M T−2 I−1 pseudovector field
Magnetization M Amount of magnetic moment per unit volume A m−1 L−1 I vector field
Mass fraction x Mass of a substance as a fraction of the total mass kg/kg 1 intensive
(Mass) Density (or volume density) ρ Mass per unit volume kg m−3 M L−3 intensive
Mean lifetime τ Average time for a particle of a substance to decay s T intensive
Molar concentration C Amount of substance per unit volume mol m−3 L−3 N intensive
Molar energy Amount of energy present in a system per unit amount of substance J mol−1 M L2 T−2 N−1 intensive
Molar entropy Entropy per unit amount of substance J K−1 mol−1 M L2 T−2 Θ−1 N−1 intensive
Molar heat capacity c Heat capacity of a material per unit amount of substance J K−1 mol−1 M L2 T−2 Θ−1 N−1 intensive
Moment of inertia I Inertia of an object with respect to angular acceleration kg m2 M L2 tensor, scalar
Momentum p Product of an object's mass and velocity N s M L T−1 vector, extensive
Permeability μ Measure for how the magnetization of material is affected by the application of an external magnetic field H m−1 M L T−2 I−2 intensive
Permittivity ε Measure for how the polarization of a material is affected by the application of an external electric field F m−1 M−1 L−3 T4 I2 intensive
Power P Rate of transfer of energy per unit time watt (W) M L2 T−3 extensive, scalar
Pressure p Force per unit area pascal (Pa = kg m−1 s−2) M L−1 T−2 intensive, scalar
Pop p Rate of change of crackle per unit time: the sixth time derivative of position m s−6 L T−6 vector
(Radioactive) Activity A Number of particles decaying per unit time becquerel (Bq = s−1) T−1 extensive, scalar
(Radioactive) Dose D Ionizing radiation energy absorbed by biological tissue per unit mass gray (Gy = m2 s−2) L2 T−2
Radiance L Power of emitted electromagnetic radiation per unit solid angle per emitting source area W m−2 sr−1 M T−3
Radiant intensity I Power of emitted electromagnetic radiation per unit solid angle W sr−1 M L2 T−3 scalar
Reaction rate r Rate of a chemical reaction for unit time mol m−3 s−1 N L−3 T−1 intensive, scalar
Refractive index n Factor by which the phase velocity of light is reduced in a medium unitless 1 intensive, scalar
Reluctance ${\displaystyle {\mathcal {R}}}$ resistance to the flow of magnetic flux H−1 M-1 L-2 T2 I2 scalar
Solid angle Ω Ratio of area on a sphere to its radius squared steradian (sr) 1
Speed v Moved distance per unit time: the first time derivative of position m s−1 L T−1 scalar
Specific energy Energy density per unit mass J kg−1 L2 T−2 intensive
Specific heat capacity c Heat capacity per unit mass J kg−1 K−1 L2 T−2 Θ−1 intensive
Specific volume v Volume per unit mass (reciprocal of density) m3 kg−1 M−1 L3 intensive
Spin S Quantum-mechanically defined angular momentum of a particle kg m2 s−1 M L2 T−1
Strain ε Extension per unit length unitless 1
Stress σ Force per unit oriented surface area Pa M L−1 T−2 order 2 tensor
Surface tension γ Energy change per unit change in surface area N m−1 or J m−2 M T−2
Temperature gradient ${\displaystyle \nabla T}$ steepest rate of temperature change at a particular location K m−1 Θ L−1 vector
Thermal conductivity k Measure for the ease with which a material conducts heat W m−1 K−1 M L T−3 Θ−1 intensive
Torque τ Product of a force and the perpendicular distance of the force from the point about which it is exerted newton metre (N m) M L2 T−2 bivector (or pseudovector in 3D)
Velocity v Speed and direction of an object m s−1 L T−1 vector
Volume V Three dimensional extent of an object m3 L3 extensive, scalar
Volumetric flow Q Rate of change of volume per unit time m3 s-1 L3 T-1 extensive, scalar
Wavelength λ Perpendicular distance between repeating units of a wave m L
Wavenumber k Repetency or spacial frequency: the number of cycles per unit distance m−1 L−1 scalar
Wavevector k Repetency or spacial frequency vector: the number of cycles per unit distance m−1 with direction L−1 vector
Weight w Gravitational force on an object newton (N = kg m s−2) M L T−2 vector
Work W Transferred energy joule (J = kg m2 s−2) M L2 T−2 scalar
Young's modulus E Ratio of stress to strain pascal (Pa = kg m−1 s−2) M L−1 T−2 scalar; assumes isotropic linear material