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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. [4] 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 ...
Water potential is the potential energy of water per unit volume relative to pure water in reference conditions. Water potential quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure and matrix effects such as capillary action (which is caused by surface tension).
The unusual density curve and lower density of ice than of water is essential for much of the life on earth—if water were most dense at the freezing point, then in winter the cooling at the surface would lead to convective mixing. Once 0 °C are reached, the water body would freeze from the bottom up, and all life in it would be killed. [36]
Disturbed free surface of a sea, viewed from below. In physics, a free surface is the surface of a fluid that is subject to zero parallel shear stress, [1] such as the interface between two homogeneous fluids. [2] An example of two such homogeneous fluids would be a body of water (liquid) and the air in the Earth's atmosphere (gas mixture).
The surface energy of a liquid may be measured by stretching a liquid membrane (which increases the surface area and hence the surface energy). In that case, in order to increase the surface area of a mass of liquid by an amount, δA, a quantity of work, γ δA, is needed (where γ is the surface energy density of the liquid).
As striders increase in size, their legs become proportionately longer, with Gigantometra gigas having a length of over 20 cm requiring a surface tension force of about 40 millinewtons. Water striders generate thrust by shedding vortices in the water: a series of U-shaped vortex filaments is created during the power stroke.
Interfacial and surface tension can be characterized by classical methods such as the -pendant or spinning drop method. Dynamic surface tensions, i.e. surface tension as a function of time, can be obtained by the maximum bubble pressure apparatus. The structure of surfactant layers can be studied by ellipsometry or X-ray reflectivity.
Surface tension is one of the areas of interest in biomimetics research. Surface tension forces will only begin to dominate gravitational forces below length scales on the order of the fluid's capillary length, which for water is about 2 millimeters. Because of this scaling, biomimetic devices that utilize surface tension will generally be very ...