1. The problem statement, all variables and given/known data What is the maximum kinetic energy (in keV to 3 significant figures) of an electron emitted in the beta decay of a free neutron? Write down the decay equation using accepted notation. Mass of a Neutron: 1.008665 u Mass of a Proton: 1.007276 u Mass of an Electron: 0.00054858 u the energy mass equivalence for this question is 931.5 MeV/amu 2. Relevant equations e=mc^2 beta decay equation: A / Z X -> A / (Z+1) Y + e- + v 3. The attempt at a solution beta decay equation: A / Z X -> A / (Z+1) Y + e- + v by A / Z i mean A over Z, not divided by. i really have no idea how to do this. But: for the neutron: e= mc^2 e= (1.008665 u)(2.9979x10^8 m/s)^2 e= 9.065x10^16 amu m^2 s^2 for the proton: e= (1.007276 amu)(2.9979x10^8 m/s)^2 e= 9.052x10^16 amu m^2 s^2 for the electron: e=mc^2 e= (0.00054858amu)(2.9979x10^8 m/s)^2 e= 4.93x10^13 amu m^2 s^2 if i subtract the energy of the proton from the neutron you get the energy of the electron and its KE: 9.052x10^16 - 9.065x10^16 = -1.2x10^14 amu m^2 s^2 then to get the ke of the electron: -1.2x10^14 - 4.93x10^13 = -1.693x10^14 amu m^2 s^2 I know the answer is wrong because i havent converted amu into energy. I dont get fully what they mean by "if the energy mass equivalence is 931.5 MeV/amu". I could probably convert amu -> kg, then kg -> J, then J -> MeV, then MeV -> keV BUT, i'm dont think thats what they're asking given they've stated "the energy mass equivalence is 931.5 MeV/amu" does that just mean that for 1 unit of amu = 931.5 OR to divide 931.5 BY the value i've obtained in amu. Insight appriciated :( i am quite stuck.