<P> Materials with high surface area to volume ratio (e.g. very small diameter, very porous, or otherwise not compact) react at much faster rates than monolithic materials, because more surface is available to react . Examples include grain dust; while grain isn't typically flammable, grain dust is explosive . Finely ground salt dissolves much more quickly than coarse salt . </P> <P> High surface area to volume ratio provides a strong "driving force" to speed up thermodynamic processes that minimize free energy . </P> <P> The ratio between the surface area and volume of cells and organisms has an enormous impact on their biology, including their physiology and behavior . For example, many aquatic microorganisms have increased surface area to increase their drag in the water . This reduces their rate of sink and allows them to remain near the surface with less energy expenditure . </P> <P> An increased surface area to volume ratio also means increased exposure to the environment . The finely - branched appendages of filter feeders such as krill provide a large surface area to sift the water for food . </P>

Surface area to volume ratio of a 1cm cube