rest mass

American  

noun

Physics.

1. the mass of a body as measured when the body is at rest relative to an observer, an inherent property of the body.

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rest mass British  

noun

1. the mass of an object that is at rest relative to an observer. It is the mass used in Newtonian mechanics

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rest mass Scientific  

1. In Special and General Relativity, the observed mass of a body that is not in motion with respect to the observer.

2. Also called invariant mass

3. Compare relativistic mass

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Etymology

Origin of rest mass

First recorded in 1910–15

Example Sentences

Nuclear processes could not account for their energy output, because they release only a percent fraction of their rest mass as pure energy.

From BBC • Jan. 26, 2016

Stored energy appears as increased rest mass, and so this means that there is significant uncertainty in the rest mass of short-lived particles.

From Textbooks • Aug. 12, 2015

For example, if energy is stored in the object, its rest mass increases.

From Textbooks • Aug. 12, 2015

It carries energy proportional to the radiation frequency but has zero rest mass.

From Scientific American • Oct. 14, 2013

Thus, for example, in a body at rest mass is patent, energy latent and potentiality of conscious manifestation sublatent.

From A History of Indian Philosophy, Volume 1 by Dasgupta, Surendranath