# In the equation E=mc2 why is the speed of light squared i mean what is its significance?

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You might want to look at the link below, it's a nice clear explaination complete with the math derivation, and it's not too lengthy...

here the speed of light acts only as a constant of proprtionality.....

1. look E and m are inter-convertable.....and in such processes E is directly proportional to m.......

2. now to replaceproportionality by equality we must require a constant.....

3. morever in such processes a very small amount of mass can be converted into a very very large amount of energy.....therefore the constant heree will have a very large value....and when calculated, its valuewere found to be equal to 90000000000000000 and its unit should be in m/s that is exactly equal to the square of speed of light.....