# $E=mc^2$ why is it $c^2$ and not just $c$?

Why is constant for the conversion of mass to energy square of the ligths speed? is it bedside it's the fastest real matter? .

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possible duplicate of Does $E$ really equal $mc^2$? –  Qmechanic Nov 24 '11 at 19:33
Why? Why ask? This is the way it is. We get the best experimental predictions with this law, instead of any other one. That's why. –  ja72 Nov 24 '11 at 22:29
Sorry, but this question doesn't make any sense... –  J. C. Leitão Nov 25 '11 at 15:38

Because energy in joules, and joule is $\text{kg}\cdot\frac{\text{m}^2}{\text{s}^2}$ not $\text{kg}\cdot\frac{\text{m}}{\text{s}}$.