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Physical Quantities

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A physical quantity is a physical property of a phenomenon, body, or substance, that can be quantified by measurement.[1] A physical quantity can be expressed as the combination of a magnitude expressed by a number – usually a real number – and a unit; for example, 1.6749275×10−27 kg (the mass of the neutron), or 299792458 metres per second (the speed of light). Physical quantities are measured as n u {\textstyle nu} {\textstyle nu} where n {\textstyle n} {\textstyle n} is the magnitude and u {\textstyle u} {\textstyle u} is the unit. For example: A boy measured the length of a room as 3 m. Here 3 is the magnitude and m (metre) is the unit. 3 m can also be written as 300 cm. The same physical quantity x {\textstyle x} {\textstyle x} can be represented equivalently in many unit systems, i.e. x = n 1 u 1 = n 2 u 2 {\textstyle x=n_{1}u_{1}=n_{2}u_{2}} {\textstyle x=n_{1}u_{1}=n_{2}u_{2}}.


Base quantity Symbol Description SI unit Symbol for dimension Comments
Length l The one-dimensional extent of an object. metre (m) L  
Mass m The amount of matter in an object. 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. ampere (A) I  
Temperature T Average 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 Amount of energy emitted by a light source in a particular direction. candela (cd) J scalar

This list is incomplete; you can help by expanding it.

Derived quantity
Description SI units Dimension Comments
Plane angle θ Measure of a change in direction or orientation. radian (rad) 1  
Solid angle Ω Measure of the size of an object as projected on a sphere. steradian (sr) 1  
Absorbed dose rate   Absorbed dose received per unit of time. Gy s−1 L2T−3  
Acceleration a Rate of change of the speed or velocity of an object. m s−2 L T−2 vector
Angular acceleration α Rate of change in angular speed or velocity. rad s−2 T−2  
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
Angular momentum L Measure of the extent and direction an object rotates about a reference point. kg m2 s−1 M L2T−1 conserved quantity, pseudovector
Area A The two-dimensional extent of an object. m2 L2 scalar
Area density ρA The amount of mass per unit area of a two-dimensional object. kg m−2 M L−2  
Capacitance C Measure for the amount of stored charge for a given potential. farad (F = A2 s4 kg−1 m−2) I2T4M−1L−2 scalar
Catalytic activity   Change in reaction rate due to presence of a catalyst. katal (kat = mol s−1) N T−1  
Catalytic activity concentration   Change in reaction rate due to presence of a catalyst per unit volume of the system. kat m−3 N L−3T−1  
Chemical potential μ The amount of energy needed to add a particle to a system. J mol−1 M L2T−2N−1 intensive
Molar concentration C Amount of substance per unit volume. mol m−3 N L−3 intensive
Crackle c Rate of change of Jounce. The fifth derivative of position. m s−5 L T−5 Vector
Current density J Amount of electric current flowing through a surface. A m−2 I L−2 vector
Dose equivalent H Measure for the received amount of radiation adjusted for the effect of different types of radiant on biological tissue. sievert (Sv = m2 s−2) L2T−2  
Dynamic Viscosity η Measure for the resistance of an incompressible fluid to stress. Pa s M L−1T−1  
Electric Charge Q Amount of electric charge. coulomb (C = A s) I T extensive, conserved quantity
Electric charge density ρQ Amount of electric charge per unit volume. C m−3 I T L−3 intensive
Electric displacement D Strength of the electric displacement. C m−2 I T L−2 vector field
Electric field strength E Strength of the electric field. V m−1 M L T−3I−1 vector field
Electrical conductance G Meausure for how easily current flows through a material. siemens (S = A2 s3 kg−1 m−2) L−2M−1T3I2 scalar
Electric potential V The amount of work required to bring a unit charge into an electric field from infinity. volt (V = kg m2 A−1 s−3) L2M T−3I−1 scalar
Electrical resistance R The degree to which an object opposes the passage of an electric current. ohm (Ω = kg m2 A−2 s−3) L2M T−3I−2 scalar
Energy E The capacity of a body or system to do work. joule (J = kg m2 s−2) M L2T−2 extensive, scalar, conserved quantity
Energy density ρE Amount of energy per unit volume. J m−3 M L−1T−2 intensive
Entropy S Measure for the amount of available states for a system. J K−1 M L2T−2Θ−1 extensive, scalar
Force F The cause of acceleration, acting on an object. newton (N = kg m s−2) M L T−2 vector
Fuel efficiency   Distance traveled per meter cubed.   L−2 scalar
Impulse p The cause of a change in momentum, acting on an object. kg m s−1 M L T−1 vector
Frequency f The number of times something happens in a period of time. hertz (Hz =s−1) T−1 scalar
Half-life t1/2 The time needed for a quantity to decay to half its original value. s T  
Heat Q Amount of energy transferred between systems due to temperature difference. J M L2T−2  
Heat capacity Cp Amount of energy needed to raise the temperature of a system by one degree. J K−1 M L2T−2Θ−1 extensive
Heat flux density ϕQ Amount of heat flowing through a surface per unit area. W m−2 M T−3  
Illuminance Ev Total luminous flux incident to a surface per unit area. lux (lx = cd sr m−2) J L−2  
Impedance Z Measure for the resistance of an electrical circuit against an alternating current. ohm (Ω = kg m2 A−2 s−3) M'L'2T−3I−2 complex scalar
Index of refraction n The factor by which the speed of light is reduced in a medium.   1 intensive, scalar
Inductance L Measure for the amount of magnetic flux generated for a certain current run through a circuit. henry (H = kg m2 A−2 s−2) M L2T−2I−2 scalar
Irradiance E Power of electromagnetic radiation flowing through a surface per unit area. W m−2 M T−3  
Intensity I Power per unit cross sectional area. W m−2 M T−3  
Jerk j Rate of change of acceleration. The third derivative of position. m s−3 L T−3 Vector
Jounce (or snap) s Rate of change of Jerk. The fourth derivative of position. m s−4 L T−4 Vector
Linear density ρl Amount of mass per unit length of a one-dimensional object.   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 (M = u/c) 1  
Magnetic field strength H Strength of a magnetic field in a material. A m−1 I L−1 vector field
Magnetic flux Φ Measure of quantity of magnetism, taking account of the strength and the extent of a magnetic field. weber (Wb = kg m2 A−1 s−2) M L2T−2I−1 scalar
Magnetic flux density B Measure for the strength of the magnetic field. tesla (T = kg A−1 s−2) M T−2I−1 pseudovector field
Magnetization M Amount of magnetic moment per unit volume. A m−1 I L−1 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 The amount of mass per unit volume of a three-dimensional object. kg m−3 M L−3 intensive
Mean lifetime τ Average time needed for a particle to decay. s T intensive
Molar energy   Amount of energy present is a system per unit amount of substance. J mol−1 M L2T−2N−1 intensive
Molar entropy   Amount of entropy present in a system per unit amount of substance. J K−1 mol−1 M L2T−2Θ−1N−1 intensive
Molar heat capacity c Heat capacity of a material per unit amount of substance. J K−1 mol−1 M L2T−2N−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−2I−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 I2M−1L−3T4 intensive
Power P The rate of change in energy over time. watt (W) M L2T−3 extensive, scalar
Pressure p Amount of force per unit area. pascal (Pa = kg m−1 s−2) M L−1T−2 intensive, scalar
Pop p Rate of change of crackle. The sixth 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 Amount of energy absorbed by biological tissue from ionizing radiation per unit mass. gray (unit) (Gy = m2 s−2) L2T−2  
Radiance L Power of emitted electromagnetic radiation per solid angle and per projected source area. W m−2 sr−1 M T−3  
Radiant intensity I Power of emitted electromagnetic radiation per solid angle. W sr−1 M L2T−3 scalar
Reaction rate r Measure for speed of a chemical reaction. mol m−3 s−1 N L−3T−1 intensive, scalar
Refractive Index n Measure of how light is refracted through a medium. Unitless Dimensionless  
Angle θ The space between two intersecting lines at or close to the point where they meet. rad / Degree Dimensionless  
Speed v Rate of change of the position of an object. m s−1 L T−1 scalar
Specific energy   Amount of energy present per unit mass. J kg−1 L2T−2 intensive
Specific heat capacity c Heat capacity per unit mass. J kg−1 K−1 L2T−2Θ−1 intensive
Specific volume v The volume occupied by a unit mass of material (reciprocal of density). m3 kg−1 L3M−1 intensive
Spin S Intrinsic property of particles, roughly to be interpreted as the intrinsic angular momentum of the particle. kg m2 s−1 M L2T−1  
Strain   Extension per unit length. Unitless Dimensionless  
Stress σ Amount of force exerted per surface area. Pa M L−1T−2 2-tensor. (or scalar)
Surface tension γ Amount of work needed to change the surface of a liquid by a unit surface area. N m−1 or J m−2 M T−2  
Thermal conductivity k Measure for the ease with which a material conducts heat. W m−1 K−1 M L T−3Θ−1 intensive
Torque τ Product of a force and the perpendicular distance of the force from the point about which it is exerted. N m M L2T−2 pseudovector
Velocity v Speed of an object in a chosen direction. m s−1 L T−1 vector
Volume V The three dimensional extent of an object. m3 L3 extensive, scalar
Wavelength λ Distance between repeating units of a propagating wave. m L  
Wavenumber k Reciprocal of the wavelength. m−1 L−1  
Weight w Amount of gravitation force exerted on an object. newton (N = kg m s−2) M L T−2 vector
Work W Energy dissipated by a force moving over a distance, scalar product of the force and the movement vector. joule (J = kg m2 s−2) M L2T−2 scalar
Young's modulus ε Ratio of Stress over Strain. pascal (Pa = kg m−1 s−2) M L−1T−2 scalar
Absement A Measure of sustained displacement; the first integral of displacement. m s LT vector

Unit For a Physical quantity

'Velocity of speed m/s Acceleration m/s2 Density kg/m3 Forces N /sup> |extensive |- |Heat flux density |style="text-align: center" | ″ velocity of speed vinayaka m/s density vinayaka m/s2 forces vinayaka N





` ► Acceleration (3 C, 23 P)

► Amount of substance (2 C, 26 P)

► Area (3 C, 34 P)


` ► Capacitance (2 C, 6 P)

► Physical constants (3 C, 37 P)


` ► Density (2 C, 38 P)


` ► Electric charge (1 C, 7 P)

► Electrical resistance and conductance (6 C, 16 P)

► Enthalpy (15 P)

► Entropy (3 C, 19 P, 1 F)

► Thermodynamic entropy (1 C, 40 P)


` ► Force (8 C, 69 P)


` ► Geometric measurement (4 C, 12 P)


` ► Length (6 C, 30 P)

► Logarithmic scales of measurement (1 C, 25 P)


` ► Mass (6 C, 67 P)

► Molar quantities (2 P)


` ► Power (physics) (7 C, 17 P)

► Pressure (7 C, 31 P)


` ► Rates (6 C, 67 P)


` ► Sound measurements (33 P)


` ► Temperature (8 C, 61 P)

► Time (29 C, 55 P)


` ► Velocity (4 C, 21 P)

► Viscosity (2 C, 32 P)

► Visibility (2 C, 23 P)

► Voltage (5 C, 10 P)

► Volume (4 C, 22 P)


` ANSI/ASA S1.1-2013

International System of Quantities

ISO 31

ISO/IEC 80000

List of physical quantities

Physical quantity

Quantity calculus


` Absorbed dose



Acoustic impedance


Aggregate modulus


Angular acceleration

Angular diameter distance

Angular frequency

Angular momentum

Angular velocity

API gravity

Areal velocity

Attenuation coefficient

Audio frequency


` Bollard pull

Bulk modulus


` Capacitance


Characteristic admittance

Characteristic property

Charge (physics)

Circular dichroism


Cohesion (chemistry)


Comoving distance

Conductance quantum

Couple (mechanics)




` Defining equation (physics)

Delta-v (physics)


Displacement (fluid)

Distance measures (cosmology)

Distance modulus

Dust resistant

Dynamic modulus


` Effective dose (radiation)

Effective radius


Electric charge

Electric field

Electric flux

Electric intensity

Electric potential

Electric susceptibility

Electrical measurements

Electrical mobility

Electrical resistance and conductance

Electrical resistivity and conductivity

Electrochemical gradient

Electron mobility


Energy flux


Equivalent dose

Etherington's reciprocity theorem

Excess molar quantity

Extracellular field potential


` Fermi acceleration

Field strength

Film speed




Fuel efficiency


` Gravity (chemistry)

Ground pressure

Group velocity


` Heat capacity

Heat capacity rate

Heat capacity ratio

Huber's equation


Critical relative humidity

Relative humidity



` Illuminance


Electrical impedance

Characteristic impedance

Impulse (physics)


Infinitesimal strain theory

Intensity (physics)

Intensive and extensive properties

Ion transport number

Ionic strength



` Jerk (physics)



` Length

List of electromagnetism equations

List of equations in fluid mechanics

List of equations in gravitation

List of equations in nuclear and particle physics

List of equations in quantum mechanics

List of equations in wave theory

List of materials properties

List of moments of inertia

List of photonics equations



Luminosity distance

Luminosity function

Luminous efficacy

Luminous energy

Luminous flux

Luminous intensity


` Magnetic braking

Magnetic field

Magnetic flux

Magnetic helicity

Magnetic hysteresis

Magnetic moment

Magnetic susceptibility

Magnetomotive force


Mass attenuation coefficient

Mass flux

Maximum density

Measured quantity

Mechanical impedance

Mechanical load





Molar volume

Molecular property

Moment (physics)

Moment of inertia



` Negative resistance

Neutron magnetic moment

Noise-equivalent flux density

Noise-equivalent target

Notch tensile strength

Number density


` Ohm metre

Orders of magnitude (speed)


` Particle displacement

Particle number

Particle velocity

Permeability (electromagnetism)



Persistence length

Phase (waves)

Physical coefficient

Physical property

Pinning points

Plastic crystal

Poisson's ratio

Propagation constant


` Quality (physics)

Quantum efficiency

Quartz crystal microbalance with dissipation monitoring


` Radiance

Radiant energy density

Radiant exitance

Radiant exposure

Radiant flux

Radiant intensity

Radiative flux

Radiosity (radiometry)

Rate of penetration

Electrical reactance

Reciprocal length



Refractive index

Relative density

Relative velocity

Rotational speed


` Scale of temperature

Second moment of area

Signal-to-noise ratio (imaging)

Single-particle spectrum


Sound energy

Sound energy density

Sound exposure

Sound intensity

Sound power

Sound pressure

Specific detectivity

Specific force

Specific gravity

Specific impulse


` Specific weight

Spectral power distribution


Speed of sound

Spin (physics)

Spin angular momentum of light



Surface power density


System-specific impulse


` Temperature

Thermal conductance quantum

Thermal conduction

List of thermal conductivities

Thermal conductivity

Thermal contact conductance

Thermal diffusivity

Thermal effusivity

Thermal emittance

Thermal equilibrium

Thermal expansion

Thermomass theory


Tonti diagram


Transmission loss (duct acoustics)




` Vapor quality


Volume (thermodynamics)

Volumetric flux

Volumetric heat capacity


` Waterproofing

Work (physics)


` Young's modulus

Pages in Other Languages


Physics-related lists


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