Liquid

A liquid is matter in the liquid state. After a macroscopic definition is a substance, however, opposes a fairly large resistance of a strain as good as none, a volume change (the fabric is nearly incompressible ). After a microscopic definition of a fluid is a substance whose particles are constantly moving non-periodic and no long-range order, but subject to a short-range order and their mean free path is of the order of the particle diameter.

Liquids are therefore stable in volume, form unstable and are subject to Brownian motion. The liquid state is not only a substance-specific, but also depends on external factors such as temperature and pressure. Changes such fluid their physical state, it is called a phase transition, where the term of the phase is a general term for aggregate state itself.

With the gases, the liquids are combined into the fluids.

Macroscopic Description and characteristics

The temperature-dependent volume expansion of a liquid is quantified by the volume expansion coefficient. The compression modulus is a measure of the adiabatic volume elasticity, that is, for the " compressibility " of a liquid. In zero gravity or in an absence of external forces, due to their surface tension fluids to take a spherical shape, because this shape reduces the surface. Liquids exert on the wall of the vessel in which they are located, a hydrostatic pressure, for example, the water pressure. Moving liquids are physically characterized mainly by this pressure. Practicing outside pressure on liquids, so the pressure is evenly distributed throughout the liquid. The deeper you dive a body in a fluid, the greater the hydrostatic pressure on the body. However, this does not depend only on the depth, but also on the density of the liquid. Get in flowing liquids on additional variables, which are described by the fluid dynamics, a branch of continuum mechanics.

Microscopic Description and characteristics

Due to the lack in comparison to the solid state Translationsperiodizität and constant particle fluids must (eg classical density functional theory ) are using the tools of statistical mechanics described. Important here are the atomic distribution functions. Many properties of the bulk phase of liquids can be made using molecular dynamics or Monte Carlo simulation to calculate.