Unit aP
Name attopoise
Category Dynamic Viscosity
Details In the field of dynamic viscosity, attopoise (aP) is a unit used to measure the resistance of a fluid to flow or deform under applied stress. Attopoise is derived from the centipoise (cP) unit, which itself is a non-SI unit of dynamic viscosity. The prefix "atto-" denotes extremely small values, where 1 attopoise is equal to 1 × 10⁻¹⁸ poise or 10⁻²¹ Pascal-seconds (Pa·s).

Dynamic viscosity quantifies a fluid's internal resistance to deformation by shear stress or tensile stress. In other words, it measures how "thick" or "sticky" a fluid is, thus affecting the fluid's flow rate. Generally, higher viscosity fluids require more energy to move and may change behavior under different temperature and pressure conditions.

Attopoise is a relatively uncommon unit of dynamic viscosity, as it represents extremely low viscosity values. It may be found in specific scientific research contexts requiring high precision, such as nanotechnology or low-viscosity fluid applications.