Why does e=mc2 use the speed of light.?

Question

i get the m and the e but i don't get why c (the speed of light) matters. what does that have to do with the equation

Answer 1

1.  If you didn't have SOME velocity squared, the equation would be saying that energy = mass, an obvious absurdity.

2.  To see why the particular velocity is the speed of light, look at the derivation of same in the link below or any other produced by googling "e = mc2"