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Home » Einstein’s mass-energy relation emerging out of his famous theory of relativity relates mass (m) to energy (E) as , where c is the 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 , the masses are measured in unified equivalent of 1u is 931.5 MeV.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.
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 the 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 !MeV=1.6\times 10^{-13}J, the masses are measured in unified equivalent of 1u is 931.5 MeV.
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.
CBSE | Class 11 | NCERT Exemplar | Physics | Units and Measurements
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 the 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 !MeV=1.6\times 10^{-13}J, the masses are measured in unified equivalent of 1u is 931.5 MeV.
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.

a) The energy that is comparable to a given mass can be computed using Einstein’s mass-energy relation.

1amu=1u=1.67\times 10^{-27}kg

On Applying E=mc^{2} we get,

E = 931.5 MeV

b) As E=mc^{2}

m=E/c^{2}

Which means 1u=931.5 MeV/c^{2}

The dimensionally correct relation of 1 amu will be 931.5 MeV

i

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