Table 4 Examples of SI coherent derived units whose names and symbols include

Table 4 examples of si coherent derived units whose

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Table 4. Examples of SI coherent derived units whose names and symbols include SI coherent derived units with special names and symbols SI coherent derived unit ———————————————————————————— Expressed in terms of Derived quantity Name Symbol SI base units dynamic viscosity pascal second Pa s m 1 kg s 1 moment of force newton meter N m m 2 kg s 2 surface tension newton per meter N/m kg s 2 angular velocity radian per second rad/s m m 1 s 1 = s 1 angular acceleration radian per second squared rad/s 2 m m 1 s 2 = s 2 heat flux density, watt per square meter W/m 2 kg s 3 irradiance heat capacity, entropy joule per kelvin J/K m 2 kg s 2 K 1 specific heat capacity, joule per kilogram kelvin J/(kg K) m 2 s 2 K 1 specific entropy specific energy joule per kilogram J/kg m 2 s 2 thermal conductivity watt per meter kelvin W/(m K) m kg s 3 K 1 energy density joule per cubic meter J/m 3 m −1 kg s 2 electric field strength volt per meter V/m m kg s 3 A 1 electric charge density coulomb per cubic meter C/m 3 m 3 s A surface charge density coulomb per square meter C/m 2 m 2 s A electric flux density, coulomb per square meter C/m 2 m 2 s A electric displacement permittivity farad per meter F/m m 3 kg 1 s 4 A 2 permeability henry per meter H/m m kg s 2 A 2 molar energy joule per mole J/mol m 2 kg s 2 mol 1 molar entropy, joule per mole kelvin J/(mol K) m 2 kg s 2 K 1 mol 1 molar heat capacity exposure (x and γ rays) coulomb per kilogram C/kg kg 1 s A absorbed dose rate gray per second Gy/s m 2 s 3 radiant intensity watt per steradian W/sr m 4 m 2 kg s 3 = m 2 kg s 3 radiance watt per square meter steradian W/(m 2 sr) m 2 m 2 kg s 3 = kg s 3 catalytic activity katal per cubic meter kat/m 3 m 3 s 1 mol concentration The values of several different quantities may be expressed using the same name and symbol for the SI unit. Thus for the quantity heat capacity as well as the quantity entropy, the SI unit is the joule per kelvin. Similarly for the base quantity electric current as well as the derived quantity magnetomotive force, the SI unit is the ampere. It is therefore important not to use the unit alone to specify the quantity.
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SI Units 27 This applies not only to scientific and technical texts, but also, for example, to measuring instruments (i.e. an instrument read-out should indicate both the unit and the quantity measured). A derived unit can often be expressed in different ways by combining base units with derived units having special names. Joule, for example, may formally be written newton meter, or kilogram meter squared per second squared. This, however, is an algebraic freedom to be governed by common sense physical considerations; in a given situation some forms may be more helpful than others.
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