Einstein’s mass - energy relation emerging out of his famous theory of relativity relates mass (m ) to energy (E) as E = mc ^2,
Einstein’s mass - energy relation emerging out of his famous theory of relativity relates mass (m ) to energy (E) as E = mc 2, where c is speed of light in vacuum. At the nuclear level, the magnitudes of energy are very small. The energy at nuclear level is usually measured in MeV, where 1 MeV= 1.6×10–13J; the masses are measured in unified atomic mass unit (u) where 1u = 1.67 × 10–27 kg.
(a) Show that the energy equivalent of 1 u is 931.5 MeV.
(b) A student writes the relation as 1 u = 931.5 MeV. The teacher points out that the relation is dimensionally incorrect. Write the correct relation.
1 Answers
(a) Since 1 u = 1.67 × 10–27 kg, its energy equivalent is 1.67×10–27 c2 in SI units. When converted to eV and MeV, it turns out to be 1 u º 931.5 MeV.
(b) 1 u × c2 = 931.5 MeV.