An acceptable unit that is defined from base SI units. In the SI system, there are seven base units: kilogram (kg) for mass, metre (m) for length, second (s) for time, kelvin (K) for temperature, mole (mol) for the amount of substance, ampere (A) for electrical current, and candela (cd) for luminous intensity. The newton (N) is a derived unit of force where 1 N is equal to 1 kg m s⁻². The pascal (Pa) is the derived unit for pressure where 1 Pa is equal to 1 kg m⁻¹ s⁻². See base unit and Appendix 3.