text: in what way does c (the constant for the speed of light) affect the mass to have as....? a result the energy supported by it???    i am trying to understand einstein's e=mc2 yet i do not seem to understand the relationship between the speed of light and the mass....please somebody help?? not quite sure what you are asking, but when matter is accelerated, it gains mass. the faster you go, the more massive you become. finally, at c, your mass becomes infinite. obviously, this is not possible, which is why lightspeed is not the sort of barrier that can be broken, like the sound barrier.