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[19] [20] Examples of quotients of dimension one include calculating slopes or some unit conversion factors. Another set of examples is mass fractions or mole fractions, often written using parts-per notation such as ppm (= 10 −6), ppb (= 10 −9), and ppt (= 10 −12), or perhaps confusingly as ratios of two identical units (kg/kg or mol/mol).
total mass of fat divided by total body mass, multiplied by 100: biology Kt/V: Kt/V: medicine (hemodialysis and peritoneal dialysis treatment; dimensionless time) Waist–hip ratio: waist circumference divided by hip circumference: biology Waist-to-chest ratio: waist circumference divided by chest circumference: biology Waist-to-height ratio
Mass fraction: x: Mass of a substance as a fraction of the total mass kg/kg 1: intensive (Mass) Density (or volume density) ρ: Mass per unit volume kg/m 3: L −3 M: intensive Mean lifetime: τ: Average time for a particle of a substance to decay s T: intensive Molar concentration: C: Amount of substance per unit volume mol⋅m −3: L −3 N ...
In the 1990s, neutrinos were discovered to have nonzero mass, and a quantity called the vacuum angle was found to be indistinguishable from zero. [ citation needed ] The complete Standard Model requires 25 fundamental dimensionless constants (Baez, 2011).
In other words, an area of 1 000 000 square metres and not 1000 square metres. 2 Mm 3 means two cubic megametres, or the volume of two cubes of 1 000 000 m by 1 000 000 m by 1 000 000 m, i.e. 2 × 10 18 m 3, and not 2 000 000 cubic metres (2 × 10 6 m 3).
In theoretical physics, negative mass is a hypothetical type of exotic matter whose mass is of opposite sign to the mass of normal matter, e.g. −1 kg. [1] [2] Such matter would violate one or more energy conditions and exhibit strange properties such as the oppositely oriented acceleration for an applied force orientation.
For example, the dimension of a point is zero; the dimension of a line is one, as a point can move on a line in only one direction (or its opposite); the dimension of a plane is two, etc. The dimension is an intrinsic property of an object, in the sense that it is independent of the dimension of the space in which the object is or can be embedded.
An overview of ranges of mass. To help compare different orders of magnitude, the following lists describe various mass levels between 10 −67 kg and 10 52 kg. The least massive thing listed here is a graviton, and the most massive thing is the observable universe.