kompressitavad

Kompressitavad describes the property of substances that can have their volume reduced when external pressure is applied. In science, the term refers to compressibility, a measure of how easily a material can be compressed. It applies to gases, liquids and solids, though the degree of compressibility varies widely among them.

Compressibility is commonly defined as β = −(1/V)(dV/dP) at a given temperature, and the reciprocal quantity is the bulk modulus K = 1/β. A smaller β or larger K means the material is harder to compress. For gases, β is large and decreases with pressure; for liquids and solids, β is smaller and changes more slowly with pressure and temperature. The speed of sound in a medium relates to its compressibility through roughly c^2 ≈ K/ρ for near-isentropic processes.

Gases are highly compressible under ordinary conditions, liquids are moderately compressible, and solids are very incompressible. For example, water has K ≈ 2.2 GPa (β ≈ 4.5×10^−10 Pa^−1), air at room temperature has β on the order of 10^−5 Pa^−1, and many metals have β around 10^−12 to 10^−11 Pa^−1. Values depend on temperature and pressure.

Measuring compressibility uses pressure–volume data, ultrasonic or acoustic methods, and diffraction techniques in some cases. Practically, compressibility informs engineering design, seismic studies, material science, and acoustics by describing how materials and fluids respond to pressure changes and how this affects behavior under load and wave propagation.