Table 7.5 -- Units whose label begins with M-Z

Label Symbol Quantity / Definition EQ label Code References
METRE m length (SI base unit); The length of the path travelled by light in vacuum during a time interval of 1 / 299 792 458 of a second. LENGTH 138 ISO 31-0, Table 1;
ISO 31-1, 1-3.a;
ISO 31-2, 2-5.a;
ISO 31-6, 6-3.a;
ISO 31-6, 6-45.a;
ISO 31-7, 7-5.a;
ISO 31-7, 7-10.a;
ISO 31-8, 8-38.a;
ISO 31-9, 9-8.a;
ISO 31-9, 9-17.a;
ISO 31-9, 9-26.a;
ISO 31-9, 9-27.a;
ISO 31-10, 10-17.a;
ISO 31-10, 10-21.a;
ISO 31-10, 10-33.a;
ISO 31-10, 10-39.a;
ISO 31-10, 10-41.a;
ISO 31-13, 13-1.a;
ISO 31-13, 13-3.a;
ISO 31-13, 13-7.a;
ISO 31-13, 13-8.a;
ISO 31-13, 13-16.a;
ISO 31-13, 13-34.a;
ISO 31-13, 13-39.a
METRE_FOURTH_POWER m4 second moment of area, second polar moment of area, second axial moment of area; The second axial moment of area of a plane area (section) about an axis in its plane is the sum (integral) of the products of its elements of area and the squares of their distances from the axis or point. SECOND_MOMENT_AREA 139 ISO 31-3, 3-20.a
METRE_KELVIN m · K second radiation constant; The constant c2 in the expression for the spectral concentration of the radiant exitance of a full radiator (black body). SECOND_RADIATION_CONSTANT 140 ISO 31-6, 6-20.a
METRE_PER_HOUR m/h velocity; 1 m/h = 1 / 3,6 x 10-3 m/s (exactly) VELOCITY 141 ISO 31-1, 1-10.a;
ISO 31-2, 2-8.a;
ISO 31-5, 5-32.a;
ISO 31-6, 6-6.a;
ISO 31-7, 7-11.a;
ISO 31-7, 7-14.a;
ISO 31-10, 10-30.a;
ISO 31-0, 2.3.2.3
METRE_PER_SEC m/s velocity; Distance divided by time. VELOCITY 142 ISO 31-1, 1-10.a;
ISO 31-2, 2-8.a;
ISO 31-5, 5-32.a;
ISO 31-6, 6-6.a;
ISO 31-7, 7-11.a;
ISO 31-7, 7-14.a;
ISO 31-10, 10-30.a
METRE_PER_SEC_SQD m/s2 acceleration; Change in velocity divided by time. ACCELERATION 143 ISO 31-1, 1-11.a;
ISO 31-7, 7-12.a
MINUTE min time; 1 min = 60 s (exactly) TIME 146 ISO 31-0, Table 4;
ISO 31-1, 1-7.b
MINUTE_ARC ' plane angle; The angle between two half-lines terminating at the same point is defined as the ratio of the length of the included arc of the circle (with its centre at that point) to the radius of that circle.
1' = (1 / 60)º = (π / 10 800) rad (exactly)		 PLANE_ANGLE 147 ISO 31-0, Table 4;
ISO 31-1, 1-1.c
MOLE mol amount of substance (SI base unit); The amount of substance in a system which contains as many elementary entities as there are atoms in 0,012 kilogram of carbon 12.
When the mole is used, the elementary entities must be specified, and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles.		 AMOUNT_SUBSTANCE 148 ISO 31-0, Table 1;
ISO 31-8, 8-3.a;
ISO 31-8, 8-29.a
MOLE_PER_CUBIC_M mol/m3 concentration, amount-of-substance concentration; Amount of substance divided by the volume of the mixture. CONCENTRATION 149 ISO 31-8, 8-13.a
MOLE_PER_KG mol/kg molality of solute, ionic strength; Amount of substance of solute in a solution divided by the mass of the solvent. MOLALITY_SOLUTE 150 ISO 31-8, 8-16.a;
ISO 31-8, 8-46.a
MOLE_PER_LITRE mol/l, mol/L concentration, amount-of-substance concentration; Amount of substance divided by the volume of the mixture.
1 mol/l = 103 mol/m3 (exactly)		 CONCENTRATION 151 ISO 31-8, 8-13.b
MOLE_PER_MOLE mol/mol mole fraction; dimensionless
1 mol/mol = 1		 MOLE_FRACTION 152 ISO 31-8, 8-14.a;
ISO 31-0, 2.3.3
NEPER Np field quantity ratio (level), power quantity ratio (level); Natural logarithm of a power quantity ratio, or twice the natural logarithm of a field quantity ratio.
1 Np is the level of a power quantity when 1/2 ln (P/P0) = 1 where P and P0 represent two powers of the same kind, P0 being a reference power.
1 Np is also the level of a field quantity when ln (F/F0) = 1 where F and F0 represent two amplitudes of the same kind, F0 being a reference amplitude.		 FIELD_OR_POWER_LEVEL 154 ISO 31-2, 2-9.a;
ISO 31-2, 2-10.a;
ISO 31-2, 2-12.a;
ISO 31-7, 7-25.a
NEPER_PER_SECOND Np/s damping coefficient; Sometimes used instead of 1/s in the measurement of periodic and acoustic phenomena. DAMPING_COEFFICIENT 155 ISO 31-2, 2-11.b;
ISO 31-7, 7-23.b
NEWTON N force; 1 N = 1 (m · kg)/s2 FORCE 156 ISO 31-0, Table 2;
ISO 31-3, 3-9.a
NEWTON_M_SQD_PER_KG_SQD (N · m2)/kg2 gravitational force between two particles; 1 N · m2/kg2 = 1 m3/(kg · s2) GRAVITATIONAL_FORCE 157 ISO 31-3, 3-14.a
NEWTON_METRE N · m moment of force; 1 N · m = 1 (m2 · kg2)/s2 MOMENT_FORCE 158 ISO 31-3, 3-12.a
NEWTON_METRE_SECOND N · m · s angular impulse; 1 N · m · s = 1 (m2 · kg2)/s ANGULAR_IMPULSE 159 ISO 31-3, 3-13.a
NEWTON_PER_METRE N/m surface tension; 1 N/m = 1 kg/s2 SURFACE_TENSION 160 ISO 31-3, 3-25.a
NEWTON_PER_SQ_M N/m2 pressure, stress; 1 N/m2 = 1 Pa = 1 kg/(m · s2) PRESSURE 161 ISO 31-0, Table 2;
ISO 31-3, 3-15.a;
ISO 31-3, 3-18.a;
ISO 31-7, 7-9.a;
ISO 31-8, 8-19.a;
ISO 31-8, 8-20.a;
ISO 31-8, 8-26.a
NEWTON_SECOND N · s impulse; 1 N · s = 1 (m · kg)/s IMPULSE 162 ISO 31-3, 3-10.a
NEWTON_SECOND_PER_METRE (N · s)/m mechanical impedance; At a surface (or at a point), the complex representation of total force divided by the complex representation of average particle velocity at that surface (or of particle velocity at that point) in the direction of the force.
1 (N · s)/m = 1 kg/s		 MECHANICAL_IMPEDANCE 163 ISO 31-7, 7-19.a
OCTAVE none frequency interval; The numerical value of a frequency interval in octaves is given by lb (f2/f1), when f2 is greater than f1.
The frequency interval between f1 and f2 is one octave if f2/f1 = 2		 FREQUENCY_INTERVAL 164 ISO 31-7, 7-3.a
OHM Ω electrical resistance; Electric potential difference divided by current when there is no electromotive force in the conductor.
1 Ω = 1 V/A = 1 (m2 · kg)/(s3 · A2)		 RESISTANCE 165 ISO 31-0, Table 2;
ISO 31-5, 5-33.a;
ISO 31-5, 5-44.a
OHM_METRE Ω · m resistivity; 1 Ω · m = 1 (m3 · kg)/(s3 · A2) RESISTIVITY 166 ISO 31-5, 5-36.a;
ISO 31-13, 13-18.a
PASCAL Pa pressure, stress; 1 Pa = 1 N/m2 = 1 kg/(m · s2) PRESSURE 168 ISO 31-0, Table 2;
ISO 31-3, 3-15.a;
ISO 31-3, 3-18.a;
ISO 31-7, 7-9.a;
ISO 31-8, 8-19.a;
ISO 31-8, 8-20.a;
ISO 31-8, 8-26.a
PASCAL_PER_KELVIN Pa/K pressure coefficient; 1 Pa/K = 1 kg/(m · s2 · K) PRESSURE_COEFFICIENT 169 ISO 31-4, 4-4.a
PASCAL_PER_SEC Pa/s pressure change rate; 1 Pa/s = 1 kg/(m · s3) PRESSURE_CHANGE_RATE 170 ISO 31-0, 2.3.2.2 (derived)
PASCAL_SEC Pa · s dynamic viscosity; 1 Pa · s = 1 kg/(m · s) DYNAMIC_VISCOSITY 171 ISO 31-3, 3-23.a
PASCAL_SEC_PER_CUBIC_METRE (Pa · s)/m3 acoustic impedance; At a surface, the complex representation of sound pressure divided by the complex representation of volume flow rate.
1 (Pa · s)/m3 = 1 kg/(m4 · s)		 ACOUSTIC_IMPEDANCE 172 ISO 31-7, 7-18.a
PASCAL_SEC_PER_METRE (Pa · s)/m surface density of mechanical impedance, characteristic impedance of a medium; At a surface, or at a point in a medium and for a plane progressive wave, the complex representation of sound pressure divided by the complex representation of particle velocity.
1 (Pa · s)/m = 1 kg/(m2 · s)		 SURFACE_DENSITY_MECH_IMPED 173 ISO 31-7, 7-20.a
PHON none loudness level; 1 phon is the loudness level when 2 lb (peff/p0)1 kHz = 0,1 , where peff is the root-mean-square value of the sound pressure of a pure tone of 1 kHz, which is judged by a normal observer under standardized listening conditions as being as loud as the sound under investigation, and where p0 = 20 μPa.
For a pure tone of frequency 1 kHz, 1 phon is approximately 1 dB.		 LOUDNESS_LEVEL 175 ISO 31-7, 7-31.a
RADIAN rad plane angle; dimensionless. The angle between two half-lines terminating at the same point is defined as the ratio of the length of the included arc of the circle (with its centre at that point) to the radius of that circle.
1 rad = 1 m/m = 1
A complete angle (full circle) is 2π rad.		 PLANE_ANGLE 181 ISO 31-0, Table 2;
ISO 31-1, 1-1.a;
ISO 31-5, 5-43.a;
ISO 31-5, 5-48.a;
ISO 31-8, 8-51.a;
ISO 31-13, 13-4.a
RADIAN_PER_METRE rad/m angular repetency, angular wave number; The reciprocal of the wavelength or the number of waves per unit angle along the direction of propagation. ANGULAR_REPETENCY 182 ISO 31-2, 2-7.a;
ISO 31-6, 6-5.a;
ISO 31-7, 7-7.a;
ISO 31-13, 13-10.a
RADIAN_PER_SEC rad/s angular velocity; Change in angular position divided by time. ANGULAR_VELOCITY 183 ISO 31-1, 1-8.a;
ISO 31-2, 2-4.a;
ISO 31-5, 5-42.a;
ISO 31-6, 6-2.a;
ISO 31-7, 7-4.a;
ISO 31-9, 9-14.a;
ISO 31-9, 9-15.a;
ISO 31-13, 13-11.a
RADIAN_PER_SEC_SQD rad/s2 angular acceleration; Change in angular velocity divided by time. ANGULAR_ACCELERATION 184 ISO 31-1, 1-9.a
SECOND s time (SI base unit); The duration of 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom. TIME 187 ISO 31-0, Table 1;
ISO 31-1, 1-7.a;
ISO 31-2, 2-1.a;
ISO 31-2, 2-2.a;
ISO 31-7, 7-1.a;
ISO 31-7, 7-24.a;
ISO 31-7, 7-30.a;
ISO 31-9, 9-31.a;
ISO 31-9, 9-37.a;
ISO 31-10, 10-48.a;
ISO 31-13, 13-33.a
SECOND_ARC " plane angle; 1" = (1 / 3 600)º = (π / 648 000) rad (exactly) PLANE_ANGLE 188 ISO 31-0, Table 4;
ISO 31-1, 1-1.d
SECOND_PER_CUBIC_M_RADIAN s/(m3 · rad) spectral concentration of vibrational modes (in terms of angular frequency); Number of vibrational modes in an infinitesimal interval of angular frequency, divided by the size of that interval and by volume.
1 s/(m3 · rad) = 1 s/m3 (exactly)		 SPECTRAL_CONC_VIBRAT_MODES 189 ISO 31-13, 13-13.a
SECOND_PER_CUBIC_METRE s/m3 spectral concentration of vibrational modes (in terms of angular frequency); Number of vibrational modes in an infinitesimal interval of angular frequency (dimensionless), divided by the size of that interval and by volume. SPECTRAL_CONC_VIBRAT_MODES 190 ISO 31-13, 13-13.b
SEIMENS_M_SQD_PER_MOLE (S · m2)/mol molar conductivity; Conductivity divided by the amount-of-substance concentration.
1 (S · m2)/mol = 1 (s3 · A2)/(kg · mol)		 MOLAR_CONDUCTIVITY 191 ISO 31-8, 8-49.a
SIEMENS S electrical conductance; 1 S = 1 Ω-1 = 1 (s3 · A2)/(m2 · kg) ELECTRIC_CONDUCTANCE 192 ISO 31-0, Table 2;
ISO 31-5, 5-34.a;
ISO 31-5, 5-45.a
SIEMENS_PER_METRE S/m electrical conductivity; Electrolytic current density divided by the electric field strength.
1 S/m = 1 (s3 · A2)/(m3 · kg)		 ELECTRIC_CONDUCTIVITY 193 ISO 31-5, 5-37.a;
ISO 31-8, 8-48.a
SIEVERT Sv dose equivalent (ionizing radiation); 1 Sv = 1 J/kg = 1 m2/s2 DOSE_EQUIVALENT 194 ISO 31-0, Table 3;
ISO 31-10, 10-52.a
SONE none loudness; A normal observer's auditory estimate of the ratio between the strength of the sound considered and that of a reference sound having a loudness level of 40 phons.
A standard relation between loudness in sones and loudness level in phons has been adopted for practical use and is given in ISO 131.		 LOUDNESS 195 ISO 31-7, 7-32.a
SQ_METRE m2 area AREA 196 ISO 31-1, 1-5.a;
ISO 31-7, 7-29.a;
ISO 31-9, 9-16.a;
ISO 31-10, 10-3.a;
ISO 31-10, 10-16.a;
ISO 31-10, 10-40.a
SQ_METRE_AMP_PER_JOULE_SEC (m2 · A)/(J · s) gyromagnetic coefficient, (gyromagnetic ratio); The ratio of the magnetic moment to the intrinsic angular momentum of a spinning particle.
1 (m2 · A)/(J · s) = 1 (s · A)/kg		 GYROMAGNETIC_COEFFICIENT 197 ISO 31-9, 9-12.a
SQ_METRE_AMPERE m2 · A magnetic moment, electromagnetic moment; Vector quantity, the vector product of which with the magnetic flux density of a homogeneous field is equal to the torque. MAGNETIC_MOMENT 198 ISO 31-5, 5-27.a;
ISO 31-9, 9-11.a
SQ_METRE_KELVIN_PER_WATT (m2 · K)/W thermal insulance, coefficient of thermal insulation; Temperature difference divided by areic heat flow rate.
1 (m2 · K)/W = 1 (s3 · K)/kg		 THERMAL_INSULANCE 199 ISO 31-4, 4-11.a
SQ_METRE_PER_JOULE m2/J spectral cross-section; Cross-section for a process in which the energy of the ejected or scattered particle is in an element of energy, divided by this element.
1 m2/J = 1 s2/kg		 SPECTRAL_CROSS_SECTION 200 ISO 31-10, 10-5.a
SQ_METRE_PER_JOULE_SR m2/(J · sr) spectral angular cross-section; Cross-section for ejecting or scattering a particle into an element of solid angle with energy in an element of energy, divided by the product of these two elements.
1 m2/(J · sr) = 1 s2/(kg · sr)		 SPECTRAL_ANGULAR_CROSS_SECT 201 ISO 31-10, 10-6.a
SQ_METRE_PER_KG m2/kg mass attenuation coefficient; The linear attenuation coefficient divided by the volumic mass of the substance.
mass energy transfer coefficient		 MASS_ATTENUATION_COEFF 202 ISO 31-10, 10-14.a;
ISO 31-10, 10-57.a
SQ_METRE_PER_MOLE m2/mol molar absorption coefficient, molar attenuation coefficient; The linear attenuation coefficient divided by the volumic amount of the substance. MOLAR_ABSORPTION_COEFF 203 ISO 31-6, 6-43.a;
ISO 31-10, 10-15.a
SQ_METRE_PER_SECOND m2/s kinematic viscosity
diffusion coefficient, thermal diffusion coefficient, thermal diffusivity		 KINEMATIC_VISCOSITY 204 ISO 31-3, 3-24.a;
ISO 31-4, 4-14.a;
ISO 31-8, 8-39.a;
ISO 31-8, 8-41.a;
ISO 31-10, 10-32.a
SQ_METRE_PER_STERADIAN m2/sr angular cross-section; Cross-section for ejecting or scattering a particle into an element of solid angle, divided by this element. ANGULAR_CROSS_SECTION 205 ISO 31-10, 10-4.a
SQ_METRE_PER_VOLT_SECOND m2/(V · s) mobility; Average drift velocity imparted to a charged particle in a medium by an electric field, divided by the field strength.
1 m2/(V · s) = 1 (s2 · A)/kg		 MOBILITY 206 ISO 31-10, 10-26.a
SQ_METRE_RADIAN_PER_KG (m2 · rad)/kg massic optical rotatory power, specific optical rotatory power; The cross-sectional area of a linearly polarized light beam times its angle of optical rotation, divided by the mass of the optically active component in the path. MASSIC_OPTICAL_ROT_POWER 207 ISO 31-8, 8-53.a
SQ_METRE_RADIAN_PER_MOLE (m2 · rad)/mol molar optical rotatory power; The cross-sectional area of a linearly polarized light beam times its angle of optical rotation, divided by the amount of substance of the optically active component in the path. MOLAR_OPTICAL_ROT_POWER 208 ISO 31-8, 8-52.a
STERADIAN sr solid angle; dimensionless
The solid angle of a cone is defined as the ratio of the area cut out on a spherical surface (with its centre at the apex of that cone) to the square of the radius of the sphere.
1 sr = 1 m2/m2 = 1
A complete angle over all space (full sphere) is 4π sr.		 SOLID_ANGLE 209 ISO 31-0, Table 2;
ISO 31-1, 1-2.a
TEC none total electron count, areal electron density; At a given point in space, the number of electrons incident on a small sphere, divided by the cross-sectional area of that sphere.
1 TEC = 1016 1/m2 (exactly)		 AREAL_ENTITY_DENSITY 210 ISO 31-6, 6-28.a;
ISO 31-10, 10-8.a
TESLA T magnetic flux density; 1 T = 1 Wb/m2 = 1 kg/(s2 · A) MAGNETIC_FLUX_DENSITY 211 ISO 31-0, Table 2;
ISO 31-5, 5-19.a;
ISO 31-5, 5-29.a;
ISO 31-13, 13-37.a
TONNE t mass; In the English language also called the metric ton.
1 t = 1 000 kg (exactly)		 MASS 213 ISO 31-0, Table 4;
ISO 31-3, 3-1.b
TONNE_PER_CUBIC_METRE t/m3 volumic mass, mass density, density; Mass divided by volume. In the English language also called metric ton per cubic metre.
1 t/m3 = 103 kg/m3 (exactly)		 VOLUMIC_MASS 214 ISO 31-3, 3-2.b
UNIFIED_AMASS_UNIT u mass (molecular); Its value is determined experimentally and is equal to (1 / 12) of the mass of an atom of the nuclide 12C; 1 u = 1,660 540 x 10-27 kg (approximately) MASS 215 ISO 31-0, Table 6;
ISO 31-8, 8-31.b;
ISO 31-9, 9-4.b;
ISO 31-9, 9-5.b;
ISO 31-9, 9-28.b
UNITLESS 1 (often omitted) special, pure number; dimensionless PURE_NUMBER 216 ISO 31-0, 2.3.3
VOLT V electric potential, potential difference, tension, electromotive force; Energy supplied by a source divided by the electric charge transported through the source.
1 V = 1 W/A = 1 (m2 · kg)/(s3 · A)		 ELECTRIC_POTENTIAL 217 ISO 31-0, Table 2;
ISO 31-5, 5-6.a;
ISO 31-13, 13-21.a;
ISO 31-13, 13-23.a
VOLT_AMP V · A apparent power; In electric power technology, active power is expressed in watts (W), apparent power in volt amperes (V · A) and reactive power in vars (var).
1 V · A = 1 (m2 · kg)/(s3 · A)		 APPARENT_POWER 218 ISO 31-5, 5-50.a;
ISO 1000, Annex A 5-49
VOLT_PER_KELVIN V/K Seebeck coefficient; The thermoelectromotive force between two substances divided by the temperature of their hot junction.
Thomson coefficient; Thomson heat power developed divided by the electric current and temperature difference.
1 V/K = 1 (m2 · kg)/(s3 · A · K)		 SEEBECK_COEFFICIENT 219 ISO 31-13, 13-22.a, ISO 31-13, 13-24.a
VOLT_PER_METRE V/m electric field strength; Force, exerted by electric field on an electric point charge, divided by the electric charge.
1 V/m = 1 N/C = 1 (m · kg)/(s3 · A)		 ELECTRIC_FIELD_STRENGTH 220 ISO 31-5, 5-5.a
VOLT_SQD_PER_KELVIN_SQD V2/K2 Lorenz coefficient; The thermal conductivity divided by the electrical conductivity and the thermodynamic temperature.
1 V2/K2 = 1 (m4 · kg2)/(s6 · A2 · K2)		 LORENZ_COEFFICIENT 221 ISO 31-13, 13-19.a
WATT W power; Rate of energy transfer.
1 W = 1 J/s = 1 (m2 · kg)/s3		 POWER 222 ISO 31-0, Table 2;
ISO 31-3, 3-27.a;
ISO 31-4, 4-7.a;
ISO 31-5, 5-35.a;
ISO 31-5, 5-49.a;
ISO 31-6, 6-10.a;
ISO 31-7, 7-16.a
WATT_HOUR W · h active energy; Especially electrical energy. 1 W · h = 3 600 J (exactly) ENERGY 223 ISO 31-5, 5-52.b
WATT_PER_KELVIN W/K thermal conductance; Reciprocal thermal resistance.
1 W/K = 1 (m2 · kg)/(s3 · K)		 THERMAL_CONDUCTANCE 224 ISO 31-4, 4-13.a
WATT_PER_METRE_K W/(m · K) thermal conductivity; Areic heat flow rate divided by temperature gradient.
1 W/(m · K) = 1 (m · kg)/(s3 · K)		 THERMAL_CONDUCTIVITY 225 ISO 31-4, 4-9.a
WATT_PER_SQ_CM_SEC W/(cm2 · s) radiant exitance rate; At a point on a surface, the radiant energy flux leaving the element of the surface over an interval of time, divided by the area of that element and that time.
1 W/(cm2 · s) = 10-4 W/(m2 · s) (exactly)		 RADIANT_EXITANCE_RATE 226 ISO 31-0, 2.3.2.3 (derived)
WATT_PER_SQ_M_HZ W/(m2 · Hz) flux density (frequency dependent); 1 W/(m2 · Hz) = 1 kg/s2 FLUX_DENSITY 227 ISO 31-0, 2.3.1 and 2.3.2 (derived)
WATT_PER_SQ_M_K_FOURTH_PWR W/(m2 · K4) Stefan-Boltzmann constant; The constant relating the power per unit area emitted by a radiating black body to its thermodynamic temperature.
1 W/(m2 · K4) = 1 kg/(s3 · K4)		 STEFAN_BOLTZMAN_CONSTANT 228 ISO 31-6, 6-18.a
WATT_PER_SQ_METRE W/m2 irradiance, flux density; At a point on a surface, the radiant energy flux incident on (or leaving an) an element of the surface, divided by the area of that element.
areic heat flow rate; Heat flow rate divided by area.
1 W/m2 = 1 kg/s3		 IRRADIANCE 229 ISO 31-4, 4-8.a;
ISO 31-5, 5-31.a;
ISO 31-6, 6-12.a;
ISO 31-6, 6-15.a;
ISO 31-6, 6-16.a;
ISO 31-7, 7-17.a;
ISO 31-10, 10-11.a
WATT_PER_SQ_METRE_K W/(m2 · K) coefficient of heat transfer; Heat flow rate divided by area.
1 W/(m2 · K) = 1 kg/(s3 · K)		 COEFFICIENT_HEAT_TRANSFER 230 ISO 31-4, 4-10.a
WATT_PER_SQ_METRE_MICRON W/(m2 · μm) integrated spectral radiance, spectral sterance; At a point on a surface and integrated over all directions, the radiant intensity of an element of the surface, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction, as a function of radiant wavelength.
1 W/(m2 · μm) = 1 kg/(s3 · μm)		 SPECTRAL_RADIANCE_INTEGRATE 231 ISO 31-0, 2.3.2.2 (derived)
WATT_PER_SQ_METRE_SEC W/(m2 · s) radiant exitance rate; At a point on a surface, the radiant energy flux leaving the element of the surface over an interval of time, divided by the area of that element and that time.
1 W/(m2 · s) = 1 kg/s4		 RADIANT_EXITANCE_RATE 232 ISO 31-0, 2.3.2.2 (derived)
WATT_PER_SQ_METRE_SR W/(m2 · sr) total radiance; At a point on a surface and in a given direction, the spectrally integrated radiant intensity of an element of the surface, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction.
1 W/(m2 · sr) = 1 kg/(s3 · sr)		 RADIANCE 233 ISO 31-6, 6-14.a
WATT_PER_SQ_METRE_SR_MICRON W/(m2 · sr · μm) spectral radiance, spectral sterance; At a point on a surface and in a given direction, the radiant intensity of an element of the surface, divided by the area of the orthogonal projection of this element on a plane perpendicular to the given direction, as a function of radiant wavelength.
1 W/(m2 · sr · μm) = 1 kg/(s3 · sr · μm)		 SPECTRAL_RADIANCE 234 ISO 31-0, 2.3.2.2 (derived)
WATT_PER_STERADIAN W/sr radiant intensity; In a given direction from a source, the radiant energy flux leaving the source, or an element of the source, in an element of solid angle containing the given direction, divided by that element of solid angle.
1 W/sr = 1 (m2 · kg)/(s3 · sr)		 RADIANT_INTENSITY 235 ISO 31-6, 6-13.a
WATT_SECOND W · s active energy; especially electrical energy. 1 W · s = 1 J (exactly) ENERGY 236 ISO 31-0, Table 2;
ISO 31-0, 2.3.2.2 (derived)
WATT_SQ_METRE W · m2 first radiation constant; The constant c1 in the expression for the spectral concentration of the radiant exitance of a full radiator (black body).
1 W · m2 = 1 (m4 · kg)/s3		 FIRST_RADIATION_CONSTANT 237 ISO 31-6, 6-19.a
WEBER Wb magnetic flux; Across a surface element, the scalar product of the magnetic flux density and the surface element.
1 Wb = 1 V · s = 1 (m2 · kg)/(s2 · A)		 MAGNETIC_FLUX 238 ISO 31-0, Table 2;
ISO 31-5, 5-20.a;
ISO 31-13, 13-41.a
WEBER_PER_METRE Wb/m magnetic vector potential; Vector quantity, the rotation (curl) of which is equal to the magnetic flux density.
1 Wb/m = 1 (m · kg)/(s2 · A)		 MAGNETIC_VECTOR_POTENTIAL 239 ISO 31-5, 5-21.a