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2019 definition: The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380 649 × 10 −23 when expressed in the unit J⋅K −1, which is equal to kg⋅m 2 ⋅s −2 ⋅K −1, where the kilogram, metre and second are defined in terms of h, c and ...
Gy = J/kg = kg m 2 /s 2 / kg = m 2 /s 2; S = 1/Ω = 10 −7 s / k A m H = Ω s = 10 7 k A m; Because the magnitude of many of the units composing the SI system of measurement was until 2019 defined by its mass, the quality of the IPK was diligently protected to preserve the integrity of the SI system.
The litre (Commonwealth spelling) or liter (American spelling) (SI symbols L and l, [1] other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm 3 ), 1000 cubic centimetres (cm 3 ) or 0.001 cubic metres (m 3 ).
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The International Committee for Weights and Measures (CIPM) approved a revision in November 2018 that defines the kilogram by defining the Planck constant to be exactly 6.626 070 15 × 10 −34 kg⋅m 2 ⋅s −1, effectively defining the kilogram in terms of the second and the metre. The new definition took effect on 20 May 2019. [6] [7] [29]
The mass of one breath is approximately a gram (0.5-5 g). A litre of air weighs about 1.2 g (1.2 kg/m 3). [20] A half litre ordinary tidal breath [11] weighs 0.6 g; a maximal 4.8 litre breath (average vital capacity for males) [11] weighs approximately 5.8 g.
A long ton, also called the weight ton (W/T), [1] imperial ton, or displacement ton, is equal to: . 2,240 pounds (1,016.0 kilograms; 1.0160 metric tons) exactly 12% more than the 2,000 pounds of the North American short ton, being 20 long hundredweight (112 lb) rather than 20 short hundredweight (100 lb)
The United States system of units of 1832 is based on the system in use in Britain prior to the introduction to the British imperial system on January 1, 1826. [6] Both systems are derived from English units, a system which had evolved over the millennia before American independence, and which had its roots in both Roman and Anglo-Saxon units.