# Rest Mass

• (noun): (physics) the mass of a body as measured when the body is at rest relative to an observer, an inherent property of the body.

### Some articles on rest mass, rest, mass:

Relativistic Mass Distortion - The Mass of Composite Systems
... The rest mass of a composite system is not the sum of the rest masses of the parts, unless all the parts are at rest ... The total mass of a composite system includes the kinetic energy and field energy in the system ... Given the total energy E and the length (magnitude) p of the total momentum vector, the invariant mass is given by In a mathematical system where c = 1 ...
Relativistic Mass Distortion - Conservation Versus Invariance of Mass in Special Relativity - Closed (meaning Totally Isolated) Systems
... laws in special relativity (for energy, mass, and momentum) require isolated systems, meaning systems that are totally isolated, with no mass-energy ... The invariant mass of the system is also conserved, but does not change with different observers ... with single particles all observers calculate the same particle rest mass (a special case of the invariant mass) no matter how they move (what inertial frame they choose), but ...
Relativistic Mass Distortion
... Mass in special relativity incorporates the general understandings from the concept of mass-energy equivalence ... to this concept is an additional complication resulting from the fact that "mass" is defined in two different ways in special relativity one way defines mass ("rest mass" or "invariant mass") as an invariant ... The term mass in special relativity usually refers to the rest mass of the object, which is the Newtonian mass as measured by an observer moving along with ...
Yocto
... It can be used to state a subatomic particle's mass, for example Rest mass of electron 0.000911 yg Rest mass of proton 1.6726 yg Rest mass of neutron 1.6749 yg Atomic mass unit 1.6605 yg Metric prefixes ...
Relativistic Mass Distortion - The Relativistic Mass Concept - Relativistic Mass
... In special relativity, an object that has a mass cannot travel at the speed of light ... following Lorentz and Einstein, the terms longitudinal and transverse mass were still in use ... However, those expressions were replaced by the concept of relativistic mass, an expression which was first defined by Richard C ...

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