1. The problem statement, all variables and given/known data A 67-Zn nucleus is at rest and in its first excited state, 93.3 keV above the ground state. The nucleus then decays to the ground state with the emission of a gamma ray. (One atomic mass unit is 931.5 MeV/c2.) What is the recoil speed of the nucleus? (You can assume non-relativistic motion, if needed.) 2. Relevant equations Kz=Pz2/2m Eg=Pgc Eg+Kz=93.3 keV Where Pz=Pg in magnitude 3. The attempt at a solution There's no point for me to type everything I did, but I'll describe it. I solved for P2 in each equation and set them equal to each other: Kz2m=Eg2/c2 then I used Eg+Kz=93.3 keV to substitute and I attempted to solve using the quadratic equation. However, a few times now I've gotten the Kz to be greater than 93.3keV by itself, which is obviously not right.