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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 ...
The term "plasma density" by itself usually refers to the electron density , that is, the number of charge-contributing electrons per unit volume. The degree of ionization α {\displaystyle \alpha } is defined as fraction of neutral particles that are ionized:
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 ...
Mass can be experimentally defined as a measure of the body's inertia, meaning the resistance to acceleration (change of velocity) when a net force is applied. [1] The object's mass also determines the strength of its gravitational attraction to other bodies. The SI base unit of mass is the kilogram (kg).
A black hole is a region of spacetime where gravity is so strong that nothing, including light and other electromagnetic waves, is capable of possessing enough energy to escape it. [2] Einstein 's theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole.
Centrifugation is a mechanical process which involves the use of the centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity and rotor speed. [1] The denser components of the mixture migrate away from the axis of the centrifuge, while the less dense components of the mixture migrate ...
Natural density. In number theory, natural density, also referred to as asymptotic density or arithmetic density, is one method to measure how "large" a subset of the set of natural numbers is. It relies chiefly on the probability of encountering members of the desired subset when combing through the interval [1, n] as n grows large.
The power spectral density (PSD) of the signal describes the power present in the signal as a function of frequency, per unit frequency. Power spectral density is commonly expressed in watts per hertz (W/Hz). When a signal is defined in terms only of a voltage, for instance, there is no unique power associated with the stated amplitude.