Si

2. SI - a complete metric system of units of measurement for scientists; fundamental quantities are length (meter) and mass (kilogram) and time (second) and electric current (ampere) and temperature (kelvin) and amount of matter (mole) and luminous intensity (candela); "Today the United States is the only country in the world not totally committed to the Systeme International d'Unites"

Understand the concept of derived units of measurement The 1960 International System builds on the MKS system. Its seven basic units, from which other units are derived, were defined as follows: for length, the −7 newton per metre of length; for 12 1/ 683 On May 20, 2019, the CGPM redefined the kilogram, the ampere, the mole, and the kelvin in terms of fundamental physical constants. For the kilogram, the constant chosen was −34 −19 −23 joule per kelvin, and the mole was redefined such that the 23 per mole. Widely used units in the SI system A list of the widely used units in the SI system is provided in the table. International System of Units (SI) unit abbreviation physical quantity Base units metre m length second s time kilogram kg mass ampere A electric current kelvin K thermodynamic temperature candela cd luminous intensity mole mol amount of substance unit abbreviation number of metres approximate U.S. equivalent Length kilometre km 1,000 0.62 mile centimetre cm 0.01 0.39 inch millimetre mm 0.001 0.039 inch micrometre μm 0.000001 0.000039 inch nanometre nm 0.000000001 0.000000039 inch unit abbreviation number of square metres approximate U.S. equivalent Area square kilometre sq km, or km 2 1,000,000 0.3861 square mile hectare ha 10,000 2.47 acres are a 100 119.60 square yards square centimetre sq cm, or cm 2 0.0001 0.155 square inch unit abbreviation number of cubic metres approximate U.S. equivalent Volume cubic metre m 3 1 1.307 cubic yards cubic centimetre cu cm,...