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Density ( volumetric mass density or specific mass) is a substance's mass per unit of volume. The symbol most often used for density is ρ (the lower case Greek letter rho ), although the Latin letter D can also be used. Mathematically, density is defined as mass divided by volume: [1] where ρ is the density, m is the mass, and V is the volume ...
On 31 July 1931, Austin M. Patterson, the dictionary's chemistry editor, sent in a slip reading "D or d, cont./density." This was intended to add " density " to the existing list of words that the letter "D" can abbreviate. The phrase "D or d" was misinterpreted as a single, run-together word: Dord. This was a plausible mistake because ...
Archimedes was born c. 287 BC in the seaport city of Syracuse, Sicily, at that time a self-governing colony in Magna Graecia. The date of birth is based on a statement by the Byzantine Greek scholar John Tzetzes that Archimedes lived for 75 years before his death in 212 BC. [8] In the Sand-Reckoner, Archimedes gives his father's name as Phidias ...
An important parameter determining the future evolution of the universe theory is the density parameter, Omega (Ω), defined as the average matter density of the universe divided by a critical value of that density. This selects one of three possible geometries depending on whether Ω is equal to, less than, or greater than 1. These are called ...
Outer space (or simply space) is the expanse beyond celestial bodies and their atmospheres. It contains ultra-low levels of particle densities, constituting a near-perfect vacuum [1] of predominantly hydrogen and helium plasma, permeated by electromagnetic radiation, cosmic rays, neutrinos, magnetic fields and dust.
Population density is the number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county, city, country, another territory or the entire world . The world's population is around 8,000,000,000 [3 ...
The International Astronomical Union 's. definition of a planet in the Solar System. Object is in orbit around the Sun. Object has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape. Object has cleared the neighbourhood around its orbit.
Physical property. A physical property is any property of a physical system that is measurable. [1] The changes in the physical properties of a system can be used to describe its changes between momentary states. A quantifiable physical property is called physical quantity. Measurable physical quantities are often referred to as observables.