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In fluid mechanics, Kelvin's circulation theorem (named after William Thomson, 1st Baron Kelvin who published it in 1869) states: [1][2] In a barotropic, ideal fluid with conservative body forces, the circulation around a closed curve (which encloses the same fluid elements) moving with the fluid remains constant with time. Stated mathematically:
The original form of the Kelvin equation, published in 1871, is: [1] where: = vapor pressure at a curved interface of radius. = vapor pressure at flat interface ( ) =. = surface tension. = density of vapor. = density of liquid. , = radii of curvature along the principal sections of the curved interface. This may be written in the following form ...
Comparison of temperature scales. * Normal human body temperature is 36.8 °C ±0.7 °C, or 98.2 °F ±1.3 °F. The commonly given value 98.6 °F is simply the exact conversion of the nineteenth-century German standard of 37 °C. Since it does not list an acceptable range, it could therefore be said to have excess (invalid) precision.
The 19th century British scientist Lord Kelvin first developed and proposed the scale. [5] It was often called the "absolute Celsius" scale in the early 20th century. [6] The kelvin was formally added to the International System of Units in 1954, defining 273.16 K to be the triple point of water.
Kelvin and his brother James Thomson confirmed the relation experimentally in 1849–50, and it was historically important as a very early successful application of theoretical thermodynamics. [5] Its relevance to meteorology and climatology is the increase of the water-holding capacity of the atmosphere by about 7% for every 1 °C (1.8 °F ...
The thermodynamic properties of materials are intensive thermodynamic parameters which are specific to a given material. Each is directly related to a second order differential of a thermodynamic potential. Examples for a simple 1-component system are: where P is pressure, V is volume, T is temperature, S is entropy, and N is the number of ...
The first derivatives of the internal energy with respect to its (extensive) natural variables S and V yields the intensive parameters of the system - The pressure P and the temperature T . For a simple system in which the particle numbers are constant, the second derivatives of the thermodynamic potentials can all be expressed in terms of only ...
Supercritical ethane, fluid. [1] In thermodynamics, a critical point (or critical state) is the end point of a phase equilibrium curve. One example is the liquid–vapor critical point, the end point of the pressure–temperature curve that designates conditions under which a liquid and its vapor can coexist. At higher temperatures, the gas ...