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. Note that the angle and solid angle are included in this list but are actually dimensionless quantities. The second table list the other physical quantities.
Note : 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 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 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 |
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| Derived quantity | Symbol | 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 | L2 T−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 L2 T−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) | I2 T4 M−1 L−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−3 T−1 | ||
| Chemical potential | μ | The amount of energy needed to add a particle to a system. | J mol−1 | M L2 T−2 N−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) | 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 | 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−3 I−1 | vector field |
| Electrical conductance | G | Meausure for how easily current flows through a material. | siemens (S = A2 s3 kg−1 m−2) | L−2 M−1 T3 I2 | 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) | L2 M T−3 I−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) | L2 M T−3 I−2 | scalar |
| Energy | E | The 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 | Amount of energy per unit volume. | J m−3 | M L−1 T−2 | intensive |
| Entropy | S | Measure for the amount of available states for a system. | J K−1 | M L2 T−2 Θ−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 L2 T−2 | |
| Heat capacity | Cp | Amount of energy needed to raise the temperature of a system by one degree. | J K−1 | M L2 T−2 Θ−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'2 T−3 I−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 L2 T−2 I−2 | scalar |
| Irradiance | E | Power of electromagnetic radiation flowing through a surface per unit area. | W m−2 | M T−2 | |
| 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 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 | 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 L2 T−2 N−1 | intensive | |
| Molar entropy | Amount of entropy present in a system 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 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 | I2 M−1 L−3 T4 | intensive |
| Power | P | The rate of change in energy over time. | watt (W) | M L2 T−3 | extensive, scalar |
| Pressure | p | Amount of 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. 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) | L2 T−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 L2 T−3 | scalar |
| Reaction rate | r | Measure for speed of a chemical reaction. | mol m−3 s−1 | N L−3 T−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 | 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 | The volume occupied by a unit mass of material (reciprocal of density). | m3 kg−1 | L3 M−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 L2 T−1 | |
| Strain | Extension per unit length. | Unitless | Dimensionless | ||
| Stress | σ | Amount of force exerted per surface area. | Pa | M L−1 T−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−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. | N m | M L2 T−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 L2 T−2 | scalar |
| Young's modulus | Ratio of Stress over Strain. | pascal (Pa = kg m−1 s−2) | M L−1 T−2 | scalar | |
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