Energy formulas follow similar rules to laws and formulas in thermodynamics; use lower case for all laws and formulas, unless named after a discoverer:
Noether’s theorem Lorentz transformations Newtonian mechanics Schrödinger equation the Hamiltonian the Lagrangian
but
theory of relativity rest mass energy four-momentum
The joule (J) is the unit for energy in the International System of Units (SI). Other commonly seen energy units include ergs, calories and kilocalories, British Thermal Units and kilowatt-hours, usually depending on the branch of science.
The watt (W) is the SI unit for power, which is 1 joule per second.
See also Units of measurement.