Nuclear fission equationShould not the energy conservation physics equation be E = − m c 2 instead of E = m c 2 because energy appears simultaneously with mass disappearance in splitting as | Δ E | = − | Δ m | c 2 ?Also what in Einstein's derivation dispenses with the factor 1 2 from the usual kinetic energy K E = 1 2 m v 2 ?Sorry about the elementary question, it remained with me for longtime.

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Nuclear fission equationShould not the energy conservation physics equation be  E  =  −  m      c    2     instead of   E  =  m      c    2  because energy appears simultaneously with mass disappearance in splitting as      |    Δ  E      |    =  −      |    Δ  m      |        c    2    ?Also what in Einstein&#039;s derivation dispenses with the factor       1    2   from the usual kinetic energy  K  E  =      1    2    m      v    2    ?Sorry about the elementary question, it remained with me for longtime.

verrainellewtzri · Accepted Answer

About your first question:  E  =  m      c    2   is not an equation that expresses energy conservation. It is an equation that relates the energy content of a physical object to its gravitating/inert mass. So for example, the equation says that, if you have a box filled with say some springs and a cold cup of tea and you open it, compress the springs and heat up the tea, adding some amount of energy   Δ  E to the system before closing the box again, then the mass of the box will increase by   Δ  E      /        c    2  Concerning your second question:The classical kinetic energy term arises from the relativistic energy as the leading term in the Taylor approximation that is valid for small momentum/velocity. The factor of 1/2 has its origin in the Taylor expansion of the square root. There are two ways to approach the problem. My preferred view is that the   m in your equation is the rest mass and the full relativistic energy momentum equation should be:  E  =            m      2              c      4        +          p      2              c      2      where   p is momentum.There are also some heretical texts that introduce a so called &quot;relativistic mass&quot;   m which is   m  =  γ      m    0   where       m    0   is the rest mass. In this sacrilegious notation,   E  =  m      c    2   is also valid outside of the rest frame of the object that you are studying and the kinetic energy term arises from a Taylor expansion of the   γ factor.

Nuclear fission equation Should not the energy conservation physics equation be E = &#

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