Dictionary · Standards & Units
Coherent derived unit
A derived unit that is a product of powers of base units with no numerical factor other than one — the newton is coherent in the SI; the kilometre per hour is not.
Related terms
More from Standards & Units
Derived quantity
A quantity in a system of quantities defined in terms of the base quantities of that system — speed, force, pressure.
VIM (JCGM 200:2012) 1.5
Base unit
A measurement unit adopted by convention for a base quantity — in the SI: second, metre, kilogram, ampere, kelvin, mole, candela.
VIM (JCGM 200:2012) 1.10
Numerical value equation
A relation between numerical values that holds only for stated units — the form most spreadsheet formulas quietly are, and the reason unit discipline matters.
VIM (JCGM 200:2012) 1.25
Base quantity
A quantity in a conventionally chosen subset of a system of quantities in which no member can be expressed in terms of the others.
VIM (JCGM 200:2012) 1.4
Quantity equation
A mathematical relation between quantities in a system of quantities, independent of units — v = l/t regardless of whether metres or inches are used.
VIM (JCGM 200:2012) 1.22
Numerical quantity value
The number in a quantity value — the 5.34 in 5.34 m: the ratio of the quantity to its unit.
VIM (JCGM 200:2012) 1.20