kilogram (kg) کیلوگرم kilogram (#)
*Fr.: kilogramme*
The basic unit of mass in the
→ *International System of Units (SI)*
and → *MKS* versions of the
→ *metric system*,
equal to 1,000 → *gram*s. The kilogram was
until 2019 defined as the
mass of the standard (international prototype) kilogram, a platinum-iridium
cylinder kept at the International Bureau of
Weights and Measures (BIPM), at Sèvre, near Paris, France. Copies of this
prototype are
kept by the standards agencies of all the major industrial nations.
A kilogram is equal to the mass of 1,000 cubic cm of water at 4°C
(→ *maximum density*).
According to the new (2019) definition, the kilogram is defined by taking the fixed
numerical value of the → *Planck constant* (*h*)
to be 6.62607015 × 10^{-34} when expressed in the unit J.s,
which is equal to kg m^{2} s^{-1}, where the meter and the
second are defined in terms of *c* and Δν Cs. → *kilo-*; → *gram*. |