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The gram (originally gramme; [1] SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one thousandth of a kilogram.. Originally defined in 1795 as "the absolute weight of a volume of pure water equal to the cube of the hundredth part of a metre [1 cm 3], and at the temperature of melting ice", [2] the defining temperature (≈0 °C) was later changed to 4 °C ...
A cubic metre of pure water at the temperature of maximum density (3.98 °C) and standard atmospheric pressure (101.325 kPa) has a mass of 1000 kg, or one tonne.At 0 °C, the freezing point of water, a cubic metre of water has slightly less mass, 999.972 kilograms.
While not an SI-unit, the litre may be used with SI units. It is equivalent to (10 cm) 3 = (1 dm) 3 = 10 −3 m 3. Many non-SI units continue to be used in the scientific, technical, and commercial literature. Some units are deeply embedded in history and culture, and their use has not been entirely replaced by their SI alternatives.
A significant characteristic of the metric system is its use of decimal multiples – powers of 10. For example, a length that is significantly longer or shorter than 1 metre can be represented in units that are a power of 10 or 1000 metres. This differs from many older systems in which the ratio of different units varied.
The specific weight, also known as the unit weight (symbol γ, the Greek letter gamma), is a volume-specific quantity defined as the weight W divided by the volume V of a material: = / Equivalently, it may also be formulated as the product of density, ρ, and gravity acceleration, g: = Its unit of measurement in the International System of Units (SI) is newton per cubic metre (N/m 3), with ...
Conventional mass is defined as follows: "For a mass at 20 °C, 'conventional mass' is the mass of a reference standard of density 8,000 kg/m 3 which it balances in air with a density of 1.2 kg/m 3." The effect is a small one, 150 ppm for stainless steel mass standards, but the appropriate corrections are made during the manufacture of all ...
The outhouse is a unit of area used in nuclear physics equal to 10 −6 barns (100 am 2 = 10 −34 m 2). The barn (b) is a unit of area used in nuclear physics equal to one hundred femtometres squared (100 fm 2 = 10 −28 m 2). The are (a) is a unit of area equal to 100 m 2. The decare (daa) is a unit of area equal to 1000 m 2.
The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.626 070 15 × 10 −34 when expressed in the unit J⋅s, which is equal to kg⋅m 2 ⋅s −1, where the metre and the second are defined in terms of c and Δν Cs. —