The total energy of a free electron moving through empty space is E=1.5mc^2, where m is the mass of the electron and c is the speed of light. What is this electron’s speed? 1. c (the speed of light) 2. 0.7453c 3. 0.8660c 4. 0.9428c 5. 0.9950c 6. 0.9999c I thought since that Etotal = 1.5mc^2 then.... Etotal = KE = .5mv^2 1.5mc^2 = .5mv^2 and solve for v (masses would cancel which is what I was looking for) What is wrong about this approach?