rest mass


Definition of rest mass

: the mass of a body exclusive of additional mass the body acquires by its motion according to the theory of relativity

Examples of rest mass in a Sentence

Recent Examples on the Web When the temperature of the Universe drops below a certain, critical threshold — a threshold set by the rest mass of each particle — fewer and fewer collisions occur that have enough energy to allow for creation to be a possibility. Ethan Siegel, Forbes, 2 Sep. 2021 While rest mass energy, gravitational potential energy, and kinetic energy are all concepts that work perfectly well with Newtonian mechanics and gravitation, the idea of gravitation radiation is inherently novel in Einstein’s General Relativity. Ethan Siegel, Forbes, 5 May 2021 The Higgs symmetry was restored early on, and so none of the Standard Model particles possessed a rest mass prior to that time. Ethan Siegel, Forbes, 21 Apr. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'rest mass.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of rest mass

1914, in the meaning defined above

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Time Traveler for rest mass

Time Traveler

The first known use of rest mass was in 1914

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Dictionary Entries Near rest mass

restless legs syndrome

rest mass


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Cite this Entry

“Rest mass.” Dictionary, Merriam-Webster, Accessed 17 Aug. 2022.

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