“density”的概念、定义、翻译、参考文献-科学参考

density

Physics

1. The mass of a substance per unit of volume. In SI units it is measured in kg m⁻³. See also relative density; vapour density.

2. See charge density.

3. See photographic density.

http://www.kayelaby.npl.co.uk/general_physics/2_2/2_2_1.html Values of densities of commonly used materials at the NPL website

Mathematics

The average density of a body is the ratio of its mass to its volume. In general, the density of a body may not be constant throughout the body. The density at a point P, denoted by ρ‎(P), is equal to the limit as Δ‎V → 0 of Δ‎m/Δ‎V, where Δ‎V is the volume of a small region containing P and Δ‎m is the mass of the part of the body occupying that small region.

Consider a rod of length l, with density ρ‎(x) at the point a distance x from one end of the rod. Then the mass m of the rod is given by

$m = \int_{0}^{l} ρ (x) d x$

Chemistry

The mass of a substance per unit of volume. In SI units it is measured in kg m⁻³. See also relative density; vapour density.

Chemical Engineering

The mass of a substance per unit volume. The SI units are kg m⁻³.

Computer

1. A measure of the amount of information in a given dimension of a storage medium. The density of information on a disk is almost always a fixed number of bits per sector, sectors per track, and tracks per disk. For magnetic tape it is the amount of information recorded per unit length of tape, usually in bits per inch or bits per millimetre. In general the number of flux reversals per inch (or per mm) is different because of redundancy in the coding. The density is stated for a single track. A tape transport can often read tapes with different densities under program control.
2. See packing density.

Geology and Earth Sciences

Mass per unit volume, expressed in SI units as kilograms per cubic metre (kg/m³). It is determined directly, or indirectly using gravity or seismic velocity measurements. Typical densities in unconsolidated, wet sediments range between 1200 and 2600 kg/m³, and 1000 to 2000 kg/m³ if dry. Consolidated sediments range between 1600 and 3200 kg/m³. (See also nafe–drake relationships for seismic determinations of the density of sediments.) Basic igneous rocks range between 2300 and 3170 kg/m³, and metamorphic rocks are mostly in the range 2400–3100 kg/m³, with eclogite being one of the denser of the commoner metamorphic rocks, between 3200 and 3540 kg/m³. The density of the upper mantle increases with depth from about 3330 to 4000 kg/m³, below which the lower mantle systematically increases to about 5400 kg/m³ above the core. The outer core density is about 10 100 to 12 100 kg/m³; the inner core is more uniform, with a density of about 13 000 kg/m³.

单词	density
释义	density Physics 1. The mass of a substance per unit of volume. In SI units it is measured in kg m⁻³. See also relative density; vapour density. 2. See charge density. 3. See photographic density. http://www.kayelaby.npl.co.uk/general_physics/2_2/2_2_1.html Values of densities of commonly used materials at the NPL website Mathematics The average density of a body is the ratio of its mass to its volume. In general, the density of a body may not be constant throughout the body. The density at a point P, denoted by ρ‎(P), is equal to the limit as Δ‎V → 0 of Δ‎m/Δ‎V, where Δ‎V is the volume of a small region containing P and Δ‎m is the mass of the part of the body occupying that small region. Consider a rod of length l, with density ρ‎(x) at the point a distance x from one end of the rod. Then the mass m of the rod is given by $m = \int_{0}^{l} ρ (x) d x$ Chemistry The mass of a substance per unit of volume. In SI units it is measured in kg m⁻³. See also relative density; vapour density. Chemical Engineering The mass of a substance per unit volume. The SI units are kg m⁻³. Computer 1. A measure of the amount of information in a given dimension of a storage medium. The density of information on a disk is almost always a fixed number of bits per sector, sectors per track, and tracks per disk. For magnetic tape it is the amount of information recorded per unit length of tape, usually in bits per inch or bits per millimetre. In general the number of flux reversals per inch (or per mm) is different because of redundancy in the coding. The density is stated for a single track. A tape transport can often read tapes with different densities under program control. 2. See packing density. Geology and Earth Sciences Mass per unit volume, expressed in SI units as kilograms per cubic metre (kg/m³). It is determined directly, or indirectly using gravity or seismic velocity measurements. Typical densities in unconsolidated, wet sediments range between 1200 and 2600 kg/m³, and 1000 to 2000 kg/m³ if dry. Consolidated sediments range between 1600 and 3200 kg/m³. (See also nafe–drake relationships for seismic determinations of the density of sediments.) Basic igneous rocks range between 2300 and 3170 kg/m³, and metamorphic rocks are mostly in the range 2400–3100 kg/m³, with eclogite being one of the denser of the commoner metamorphic rocks, between 3200 and 3540 kg/m³. The density of the upper mantle increases with depth from about 3330 to 4000 kg/m³, below which the lower mantle systematically increases to about 5400 kg/m³ above the core. The outer core density is about 10 100 to 12 100 kg/m³; the inner core is more uniform, with a density of about 13 000 kg/m³.
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