the total energy e of an object of mass m
Mass–energy equivalence This formula states that the equivalent energy (E) can be calculated as the mass (m) multiplied by the speed of light (c = about 7008300000000000000♠3×108 m/s) squared. Similarly, anything having energy exhibits a corresponding mass m given by its energy E divided by the speed of light squared c². Because the speed of light is a very large number in everyday units, the formula implies that even an everyday object at rest with a modest amount of mass has a very large amount of energy intrinsically. Chemical, nuclear, and other energy transformations may cause a system to lose some of its energy content (and thus some corresponding mass), releasing it as the radiant energy of light or as thermal energy for example.
TNT equivalent A gram of TNT releases 2673–6702 J (joules) upon explosion.[3] The energy liberated by one gram of TNT was arbitrarily defined as a matter of convention to be 4184 J,[4] which is exactly one kilocalorie.