Mass is equal to density times volume, or m = Dv, since density is equal to mass divided by volume, or D = m/v. Mass is denoted by the symbol "m," and its SI units are kilograms.
Mass is considered an unchanging property of an object. For example, a 1-kilogram object on Earth is still 1 kilogram on the moon despite differences in gravity that affect weight. To find weight, mass is multiplied by the acceleration of gravity.
In addition, Newton's Second Law of Motion states that force equals mass times acceleration, or F = ma. Therefore, mass is equal to force divided by acceleration, or m = F/a, as long as the mass is constant.