page47 Published March 31, 2018 at 1024 × 768 in 3/26 – 3/30/18 (FBD, Newton’s 3rd) PhySP18SS6.1.28 When you use electron Volts for your unit of mass, Einstein’s Equation goes from E = mc^2 to E=m which is so much easier to work with. Plus it reinforces the point that Energy is the same as Mass.