# Atomic Mass Unit

In nuclear physics, a convenient unit of mass is the unified atomic mass unit abbreviated as

*u*.- The amu is defined as mass of a
_{6}C^{1}atom. - 1 amu (or 1
*u*) = 1.6605402 Ã— 10^{â€“27}kg

**Masses of electron, proton, and neutron**

Mass of electron (
Mass of proton (
Mass of neutron (
Mass of hydrogen atom (

*m*) = 9.1 Ã— 10_{e}^{â€“31}kg = 0.0005486 amu*m*) = 1.6726 Ã— 10_{p}^{â€“27}kg = 1.007276 amu*m*) = 1.6750 Ã— 10_{n}^{â€“27}kg = 1.00865 amu*m*+_{e}*m*) = 1.6729 Ã— 10_{p}^{â€“27}kg = 1.0078 amu- The energy associated with a nuclear process is usually large, of the order of MeV.
- According to Einstein, mass and energy are inter convertible. The Einsteinâ€™s mass energy relationship is given by
*E*=*mc*^{2}. - If
*m*= 1 amu,*c*= 3 Ã— 10^{8}m/s, then*E*= 931 MeV, i.e., 1 amu is equivalent to 931 MeV or 1 amu (or 1 u) = 931 MeV.*u*) c^{2}= 931 MeV