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.

---

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

---

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

---

Etymology

Origin of rest mass

First recorded in 1910–15

Example Sentences

See Examples For:

rest mass

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

First, total energy is related to momentum and rest mass.

From Textbooks ● Aug. 12, 2015

It is infinite in range because its carrier particle, the graviton, has zero rest mass.

From Textbooks ● Aug. 12, 2015

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

From Scientific American ● Oct. 14, 2013

It would have produced ten thousand million times as much energy as the total disintegration of the rest mass would have produced!

From Hanging by a Thread by Randall Garrett