According to special relativity, velocity cannot be added to another velocity linearly. But I was thinking, what about kinetic energy? K.E. = mv2/2. As velocity increases, the object's mass also increases. The way I see it, the increase in mass "compensates" for the less-than-expected increase in velocity (as predicted by classical mechanics). So am I right in saying, kinetic energy can be added linearly? Does what I said above agree with relativistic K.E. equation: K.E. = ([itex]\gamma[/itex]-1)mc2 ?