Mass in special relativity the mass of a moving particle." When the relative velocity is zero, formula_33 is simply equal to 1, and the relativistic mass is reduced to the rest mass as one can see in the next two equations below. As the velocity increases toward the speed of light "c", the denominator of the right side approaches zero, and consequently formula_33 approaches infinity. In the formula for momentum the mass that occurs is the relativistic mass. In other words, the relativistic mass is the proportionality constant between the velocity and the momentum. While Newton's second law remains valid in the form the
Atomic mass constant Atomic mass constant In physics and chemistry, the atomic mass constant, "m", is one twelfth of the mass of an unbound atom of carbon-12 at rest and in its ground state. It serves to define the atomic mass unit and is, by definition, equal to 1 u. It is inverse of Avogadro constant (1/N) when expressed in grams (instead of SI unit kilogram). The CODATA recommended value is In practice, the atomic mass constant is determined as the ratio of the electron rest mass "m" to the electron relative atomic mass "A"(e) (that is, the mass of the electron on