Dichte

Dichte, in physics commonly referred to as density, describes how much mass is contained in a given volume. It is usually denoted by the symbol ρ and is measured in kilograms per cubic meter (kg/m³), though grams per cubic centimeter (g/cm³) are often used in practical contexts. By definition, ρ = m/V, where m is mass and V is volume.

Dichte depends on temperature and pressure. For most substances, density decreases as temperature increases and increases with pressure. In gases, density is especially sensitive to state variables and can be described by the ideal gas law, ρ = PM/RT, where P is pressure, M is molar mass, T is temperature, and R is the gas constant.

Measurement and related concepts. Dichte can be determined directly from mass and volume measurements or by buoyancy methods. Tools include hydrometers, densimeters, and pycnometers. For powders and granular materials, two related terms are bulk density (mass per overall volume including voids) and tapped density (density after compaction). Specific gravity, or relative density, compares a substance’s density to that of water (1 g/cm³ at 4°C).

Applications and examples. Dichte is a fundamental property in geology (rock and mineral density), material science (composites and alloys), engineering, meteorology (air density), and medicine (tissue and blood densities). It helps predict buoyancy, phase behavior, and transport properties. The density of water exhibits a notable anomaly near 4°C, where its maximum density causes ice to float and influences natural processes.

See also. Density; buoyancy; specific gravity.