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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.
Characteristic property. A characteristic property is a chemical or physical property that helps identify and classify substances. The characteristic properties of a substance are always the same whether the sample being observed is large or small. Thus, conversely, if the property of a substance changes as the sample size changes, that ...
Definition and concepts. Plant density is defined as the number of plants present per unit area of ground. In nature, plant densities can be especially high when seeds present in a seed bank germinate after winter, or in a forest understory after a tree fall opens a gap in the canopy. Due to competition for light, nutrients and water ...
Relative density ( ) or specific gravity ( ) is a dimensionless quantity, as it is the ratio of either densities or weights where is relative density, is the density of the substance being measured, and is the density of the reference. (By convention , the Greek letter rho, denotes density.) The reference material can be indicated using ...
Current density, the ratio of electric current to area. Surface power density, power per unit area. Other: Number density, number of particles per unit volume, area, or length. Optical density, the absorbance of a material. Densitometry, measuring the optical density of photographic paper, photographic film and x-ray film.
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 ...
List of physical quantities. This article consists of tables outlining a number of physical quantities. The first table lists the fundamental quantities used in the International System of Units to define the physical dimension of physical quantities for dimensional analysis. The second table lists the derived physical quantities.
Volume is a measure of regions in three-dimensional space. [1] It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The definition of length and height (cubed) is interrelated with volume.