Twelve nucleons are in a one-dimensional infinite square well of length L = 3 fm.

(a) Using the approximation that the mass of a nucleon is 1 u, find the lowest energy of a nucleon in the well. Express your answer in MeV. What is the ground-state energy of the system of 12 nucleons in the well if

(b) All the nucleons are neutrons so that there can be only 2 in each state and

(c) 6 of the nucleons are neutrons and 6 are protons so that there can be 4 nucleons in each state? (Neglect the energy of Coulomb repulsion of the protons.)