1. The problem statement, all variables and given/known data The nucleus dysprosium-160 (containing 160 nucleons) acts like a spinning object with quantized angular momentum, L2 = l(l + 1) * h_bar2, and for this nucleus it turns out that l must be an even integer (0, 2, 4...). When a Dy-160 nucleus drops from the l = 2 state to the l = 0 state, it emits an 87 keV photon (87 ✕ 103 eV). h_bar = reduced planck's constant 2. Relevant equations Kinetic Energy = L2 / 2I , where I is the moment of inertia 3. The attempt at a solution Change in KE = Change in L2 / 2I = 5h_bar2 / 2I Substituting and solving for I gave me around 2*10-54 which apparently isn't the answer. Am I using the wrong formula? edit: rookie mistake, Change in KE = 6 * h_bar.... not 5.