| Abstract from DBPedia | Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This tangential force is generally referred to as the surface tension. The net effect is the liquid behaves as if its surface were covered with a stretched elastic membrane. But this analogy must not be taken too far as the tension in an elastic membrane is dependent on the amount of deformation of the membrane while surface tension is an inherent property of the liquid–air or liquid–vapour interface. Because of the relatively high attraction of water molecules to each other through a web of hydrogen bonds, water has a higher surface tension (72.8 millinewtons (mN) per meter at 20 °C) than most other liquids. Surface tension is an important factor in the phenomenon of capillarity. Surface tension has the dimension of force per unit length, or of energy per unit area. The two are equivalent, but when referring to energy per unit of area, it is common to use the term surface energy, which is a more general term in the sense that it applies also to solids. In materials science, surface tension is used for either surface stress or surface energy.表面張力（ひょうめんちょうりょく、英語: surface tension）（水面張力，水表面張力）は、液体や固体が、表面をできるだけ小さくしようとする性質のことで、界面張力の一種である。定量的には単位面積当たりの表面自由エネルギーを表し、単位はmJ/m2または、 dyn/cm 、mN/mを用いる。記号にはγ, σが用いられることが多い。 ここで[界面]とは、ある液体や固体の相が他の相と接している境界のことである。このうち、一方が液体や固体で、もう一方が気体の場合にその界面を表面という。 歴史的にはトマス・ヤングによる1805年の報告「An Essay on the Cohesion of Fluids」がその研究の始まりである。 (Source: http://dbpedia.org/resource/Surface_tension) |
