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What is unified atomic mass unit? Express it in J/c2 and MeV/c2 . |
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Answer» The unified atomic mass unit is an accepted but non-SI unit of mass. It is defined to be equal to 1/12 of the mass of a free atom of the isotope of carbon with mass number 12 which is at rest and in its ground state. It is denoted by u. Its value in SI unit is obtained experimentally. 1 u = 1.660538782 (83) × 10-27 kg, with the standard uncertainty in the last two digits given in v parenthesis. Taking, 1 u = 1.660538782 × 10-27 kg c = 2.99792458 × 108 m/s, e = 1.602176462 × 10-19 C and using the relation E = me2 { ≡ m ≡ E / c2 ), we get, 1 u = 1.49241783 × 10-10 J/c2 ≅ 1.492 × 10-10 J/c2 and 1 u = 931.494042 MeV / c2 ≅ 931.5 MeV/c2 |
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