A given coin has a mass of 3.0 g. Calculate the nuclear energy that would be required to separate all the neutrons and protons from each other. For simplicity assume that the coin is entirely made of 2963Cu atoms (of mass 62.92960 u).
Solution: Number of atoms in a 3g coin=636.023×1023×3=2.868×1022
Each copper atom has 29 protons and and 34 neutrons.
Thus, the mass defect of each atom is 29×1.00783+34×1.00867−62.92960=0.59225u.
Total mass defect of all atoms = 0.59225u×2.868×1022=1.6985×1022u.
Thus, the nuclear energy required=1.6985×1022×931MeV=1.58×1025MeV.