en.wikipedia.org/wiki/System_of_measurement

Various systems of natural units are possible. ... constant to float (i.e. it is a number that has to be determined by experiment). ... They are similar to " Schrödinger" units but set the electron mass to unity and allow the ...

en.wikipedia.org/wiki/Mass

Mass is both a property of a physical body and a measure of its resistance to acceleration when a net force is applied. The object's mass also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram (kg). .... Outside the SI system, other units of mass include: the slug ( sl) is ...

en.wikipedia.org/wiki/Imperial_units

The system of imperial units or the imperial system is the system of units first defined in the .... In the 19th and 20th centuries, the UK used three different systems for mass and .... The imperial system is one of many systems of English units.

www.nist.gov/pml/weights-and-measures/si-units-mass

Mar 30, 2011 ... The kilogram is the SI base unit of mass and is equal to the mass of the international prototype of ... OWM Contacts Systems Expand or Collapse ... All other base units have been defined in terms of fundamental constants. ... Thus, the SI unit of the quantity weight defined in this way (force) is the newton (N).

en.wikipedia.org/wiki/International_System_of_Units

The International System of Units is the modern form of the metric system, and is the most ... Derived units may be defined in terms of base units or other derived units. ... Another three base units (for temperature, amount of substance and .... The early metric systems defined a unit of weight as a base unit, while the SI defines ...

www.enotes.com/homework-help/what-unit-mass-54161

Mass is "the amount of stuff" in an object. That is, the amount of atoms and molecules present. Mass in science, is measured in the metric system using units  ...