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
Mass–energy equivalence Mass–energy equivalence In physics, mass–energy equivalence states that anything having mass has an equivalent amount of energy and vice versa, with these fundamental quantities directly relating to one another by Albert Einstein's famous formula: formula_1 This formula states that the equivalent energy () can be calculated as the mass () multiplied by the speed of light ( = about m/s) squared. Similarly, anything having energy exhibits a corresponding mass given by its energy divided by the speed of light squared . Because the speed of light is a very large number in everyday units, the formula implies that even an