# Specific quantity > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Specific_quantity > Markdown URL: https://mediated.wiki/source/Specific_quantity.md > Source: https://en.wikipedia.org/wiki/Specific_quantity > Source revision: 1339744585 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) {{short description|Quotient of a quantity by mass}} In the [natural sciences](/source/natural_sciences), including [physiology](/source/physiology) and [engineering](/source/engineering), the qualifier '''''specific''''' or '''''massic''''' typically indicates an [intensive quantity](/source/intensive_quantity) obtained by dividing an [extensive quantity](/source/extensive_quantity) of interest by ''[mass](/source/mass)''.{{cite web | title=ISO 80000-1: Quantities and units – Part 1: General | website=iso.org | url=https://www.iso.org/obp/ui/#iso:std:iso:80000:-1:ed-2:v1:en | ref={{sfnref | iso.org}} | access-date=2023-10-16}}{{cite book | url=http://media.iupac.org/publications/books/gbook/IUPAC-GB3-2ndPrinting-Online-22apr2011.pdf | title=IUPAC Green Book | publisher=IUPAC and RSC Publishing | author=Cohen, E. R. | author-link=Quantities, Units and Symbols in Physical Chemistry | year=2007 | location=Cambridge | pages=6 (20 of 250 in PDF file) | isbn=978-0-85404-433-7 | edition=3rd|display-authors=etal}} For example, [specific leaf area](/source/specific_leaf_area) is [leaf](/source/leaf) area divided by leaf mass. [Derived SI unit](/source/Derived_SI_unit)s involve [reciprocal](/source/Multiplicative_inverse) [kilogram](/source/kilogram) (kg−1), e.g., [square metre](/source/square_metre) per kilogram (m2⋅kg−1); the expression "per unit mass" is also often used. In some fields, like acoustics, "specific" can mean division by a quantity other than mass. Named and unnamed specific quantities are given for the terms below. == List == === Mass-specific quantities === Per unit of mass (short form of ''mass-specific''): * [Specific absorption rate](/source/Specific_absorption_rate), power absorbed per unit mass of tissue at a given frequency * [Specific activity](/source/Specific_activity), radioactivity in becquerels per unit mass * [Specific energy](/source/Specific_energy), defined as energy per unit mass ** [Specific internal energy](/source/Specific_internal_energy), [internal energy](/source/internal_energy) per unit mass ** [Specific kinetic energy](/source/Specific_kinetic_energy), kinetic energy of an object per unit of mass * [Specific enthalpy](/source/Specific_enthalpy), enthalpy per unit mass * [Specific enzyme activity](/source/Specific_enzyme_activity), activity per milligram of total protein * [Specific force](/source/Specific_force), defined as the non-gravitational force per unit mass * [Specific heat capacity](/source/Specific_heat_capacity), heat capacity per unit mass, unless another unit is named, such as mole-specific heat capacity, or volume-specific heat capacity * [Specific latent heat](/source/Specific_latent_heat), latent heat per unit mass * [Specific leaf area](/source/Specific_leaf_area), leaf area per unit dry leaf mass * [Specific modulus](/source/Specific_modulus), a materials property consisting of the elastic modulus per mass density of a material * [Specific orbital energy](/source/Specific_orbital_energy), orbital energy per unit mass * [Specific power](/source/Specific_power), per unit of mass (or volume or area) * [Specific relative angular momentum](/source/Specific_relative_angular_momentum), of two orbiting bodies is angular momentum divided by the reduced mass, or the cross product of the relative position and the relative velocity * [Specific surface area](/source/Specific_surface_area), per unit of mass, volume, or cross-sectional area * [Specific volume](/source/Specific_volume), volume per unit mass, i.e. the reciprocal of density * {{anchor|Mass ratio}}'''Mass ratio''', "ratio by mass", mass per unit mass, massic mass or specific mass: the ratio of two mass values (in kilogram per kilogram) === Examples of other uses === Per unit of other types. * [Brake-specific fuel consumption](/source/Brake-specific_fuel_consumption), fuel consumption per unit of braking power * [Thrust-specific fuel consumption](/source/Thrust-specific_fuel_consumption), fuel consumption per unit of thrust * [Specific acid catalysis](/source/Specific_acid_catalysis), in which the reaction rate is proportional to the concentration of the protonated solvent molecules * [Specific acoustic impedance](/source/Specific_acoustic_impedance), ratio of sound pressure to particle speed at a single frequency * [Specific capacity](/source/Specific_capacity) of a water well, quantity of water produced per (length) unit of drawdown * [Specific detectivity](/source/Specific_detectivity) of a photodetector * [Specific gas constant](/source/Specific_gas_constant), per molar mass * [Specific gravity](/source/Relative_density), also called relative density, is a dimensionless quantity defined as the ratio of the density (mass divided by volume) of a substance to the density of a given reference material * [Specific humidity](/source/Specific_humidity), mass of water vapour per unit mass dry air * [Specific impulse](/source/Specific_impulse), impulse (momentum change) per unit mass of propellant * [Specific modulus](/source/Specific_modulus), elastic modulus per mass density * [Specific speed](/source/Specific_speed), unitless figure of merit{{clarify|date=July 2023}} used to classify pump impellers (pump-specific) and turbines (turbine-specific). Ratio of performance against reference pump that needs one unit of speed to pump one unit volume per one unit hydraulic head pressure. For a turbine, it is performance measured against a reference turbine that develops one unit of power per one unit speed per one unit of hydraulic head. * [Specific storage](/source/Specific_storage), [specific yield](/source/specific_yield), and [specific capacity](/source/specific_capacity), quantify the capacity of an aquifer to release groundwater from storage per unit decline in hydraulic head pressure * [Specific strength](/source/Specific_strength), material strength (pressure required at failure) per unit material density * [Specific surface area](/source/Specific_surface_area), per unit of mass, volume, or cross-sectional area * [Specific thrust](/source/Specific_thrust), thrust per unit mass of air intake rate == See also == * {{slink|Intensive and extensive properties#Specific properties}} * [Areic quantity](/source/Areic_quantity) * [Lineic quantity](/source/Lineic_quantity) * [Molar quantity](/source/Molar_quantity) * [Volumic quantity](/source/Volumic_quantity) == References == {{reflist}} Category:Physical quantities Category:Intensive quantities Category:Quotients --- Adapted from the Wikipedia article [Specific quantity](https://en.wikipedia.org/wiki/Specific_quantity) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Specific_quantity?action=history)). 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