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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).
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 solids.
An equivalent definition of the dyne is "that force which, acting for one second, will produce a change of velocity of one centimetre per second in a mass of one gram". [3] One dyne is equal to 10 micronewtons, 10 −5 N or to 10 nsn (nanosthenes) in the old metre–tonne–second system of units. 1 dyn = 1 g⋅cm/s 2 = 10 −5 kg⋅m/s 2 = 10 ...
differential vector element of surface area A, with infinitesimally small magnitude and direction normal to surface S: square meter (m 2) differential element of volume V enclosed by surface S: cubic meter (m 3) electric field: newton per coulomb (N⋅C −1), or equivalently, volt per meter (V⋅m −1)
A basic understanding of the terminology of cleavage energy, surface energy, and surface tension is very helpful for understanding the physical state and the events that happen at a given surface, but as discussed below, the theory of these variables also yields some interesting effects that concern the practicality of adhesive surfaces in ...
Radiosity of a surface per unit frequency or wavelength. The latter is commonly measured in W⋅m −2 ⋅nm −1. This is sometimes also confusingly called "spectral intensity". J e,λ [nb 4] watt per square metre, per metre W/m 3: M⋅L −1 ⋅T −3: Radiant exitance: M e [nb 2] watt per square metre W/m 2: M⋅T −3: Radiant flux emitted ...
Non-SI units of work include the newton-metre, erg, the foot-pound, the foot-poundal, the kilowatt hour, the litre-atmosphere, and the horsepower-hour. Due to work having the same physical dimension as heat, occasionally measurement units typically reserved for heat or energy content, such as therm, BTU and calorie, are used as a measuring unit.
Comparison of surface energy, creating new surface on the left, and surface stress due to elastic deformation. Surface stress was first defined by Josiah Willard Gibbs [1] (1839–1903) as the amount of the reversible work per unit area needed to elastically stretch a pre-existing surface.