Mass

Mass
A 2 kg (4.4 lb) cast iron weight used for balances
Common symbols
m
SI unitkilogram
Extensive?yes
Conserved?yes

Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a body, until the discovery of the atom and particle physics. It was found that different atoms and different elementary particles, theoretically with the same amount of matter, have nonetheless different masses. Mass in modern physics has multiple definitions which are conceptually distinct, but physically equivalent. Mass can be experimentally defined as a measure of the body's inertia, meaning the resistance to acceleration (change of velocity) when a net force is applied.[1] The object's mass also determines the strength of its gravitational attraction to other bodies.

The SI base unit of mass is the kilogram (kg). In physics, mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that (along with gravity) determines the strength of this force.

In the Standard Model of physics, the mass of elementary particles is believed to be a result of their coupling with the Higgs boson in what is known as the Brout–Englert–Higgs mechanism.[2]

  1. ^ Bray, Nancy (28 April 2015). "Science". NASA. Archived from the original on 30 May 2023. Retrieved 20 March 2023. Mass can be understood as a measurement of inertia, the resistance of an object to be set in motion or stopped from motion.
  2. ^ "The Higgs boson". CERN. 3 April 2024. Retrieved 9 April 2024.