# Understanding the E=MC2 for multiple objects

Im actually not a very good at physics, but I was playing with this functions (just for fun and education, so this question might end at the Scifi forum), and would like to know if this logic is wrong(or right):

1. $E=mc^2$ --> $E = m(r/t)^2$ --> $t = \sqrt{\frac{mr^2}{E}}$

2. $F = G\frac{m_1m_2}{r^2}$ --> $r^2 = \frac{Gm_1m_2}{F}$

Is it possible to state something like $t = \sqrt{\frac{(m_1+m_2)Gm_1m_2}{EF}}$ ?

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It's really not clear what you think these expressions mean. I assume $r$ is some distance? Distance from what, to what? What would that last expression mean? It relates some time interval to a function of two masses, an energy, and a force. What force? which masses? The energy of what? – Colin K Jun 4 '12 at 14:38

In the first equation $r$ is the distance light would (hypothetically) travel in a vacuum in a span of time $t$. In the second equation $r$ is the distance between two point masses. So the third equation would make sense, I guess, if you shot a single photon between two point masses separated in a vacuum by a distance $r$ with exactly total energy $E$ and gravitational attraction $F$ and wanted to figure out the time $t$ it would take for the photon to close that distance, but you have no idea what the speed of light in a vacuum ($c$) is.