energy, E

https://doi.org/10.1351/goldbook.E02101
In mechanics the sum of
potential energy
and
kinetic energy
. In thermodynamics the
thermodynamic energy
or
thermodynamic energy
increase, ΔU, is the sum of
heat
and
work
brought to the system. Only changes in energy are measurable. For photons E=h νwhere h is the
Planck constant
and ν the frequency of radiation. In relativistic physics E=m c2 where c is the speed of light and m the mass.
Source:
Green Book, 2nd ed., p. 12 [Terms] [Book]