# Weight of Energy

*Most recent answer: 01/04/2015*

Q:

E = M * C^2.Many articles state that "Energy is the same as mass". The above equation shows that it is not and, in fact, energy has different unit than mass. Shouldn't it be said that mass is a property of energy?What is the weight of an amount of energy?For example, if you weigh a top spinning with energy E, will its weight, less the weight of the stationary top, equal to M * g, where M = E / C^2 ?BTW: Thank you for the welcome.

- Mehran (age 64)

Miami

- Mehran (age 64)

Miami

A:

Yes, the top spinning with kinetic energy KE will have an extra weight g*(KE/c^{2}).

On the question of what names are best, it doesn't seem to matter much. In Planck units, for example, c is dimensionless.

Mike W.

*(published on 01/04/2015)*