What Is Mean Kinetic Temperature5/6/2021
Most materials expand with temperature increase, but some materials, such as water, contract with temperature increase over some specific range, and then they are hardly useful as thermometric materials.
![]() Unsourced material may be challenged and removed. August 2012 ) ( Learn how and when to remove this template message ). It is an empirical scale that was developed by a historical progress, which led to its zero point 0 C being defined by the freezing point of water, and additional degrees defined so that 100 C was the boiling point of water, both at sea-level atmospheric pressure. Because of the 100-degree interval, it was called a centigrade scale. Since the standardization of the kelvin in the International System of Units, it has subsequently been redefined in terms of the equivalent fixing points on the Kelvin scale, and so that a temperature increment of one degree Celsius is the same as an increment of one kelvin, though they differ by an additive offset of approximately 273.15. At this temperature, matter contains no macroscopic thermal energy, but still has quantum-mechanical zero-point energy as predicted by the uncertainty principle. This does not enter into the definition of absolute temperature. ![]() If it were possible to cool a system to absolute zero, all classical motion of its particles would cease and they would be at complete rest in this classical sense. The absolute zero, defined as 0 K, is approximately equal to 273.15 C, or 459.67 F. It is known as the Kelvin scale, widely used in science and technology. The temperature of a body in its own state of thermodynamic equilibrium is always positive, relative to the absolute zero. Its numerical zero point, 0 K, is at the absolute zero of temperature. Since May, 2019, its degrees have been defined through particle kinetic theory, and statistical mechanics. It is numerically evaluated in terms of the Boltzmann constant, the value of which is defined as fixed by international convention. Previously, since 1954, the International System of Units defined a scale and unit for the kelvin as a thermodynamic temperature, by using the reliably reproducible temperature of the triple point of water as a second reference point, the first reference point being 0 K at absolute zero. The freezing point of water at sea-level atmospheric pressure occurs at approximately 273.15 K 0 C. It may be convenient to classify them as empirically and theoretically based. Empirical temperature scales are historically older, while theoretically based scales arose in the middle of the nineteenth century. For example, the length of a column of mercury, confined in a glass-walled capillary tube, is dependent largely on temperature, and is the basis of the very useful mercury-in-glass thermometer. Such scales are valid only within convenient ranges of temperature. For example, above the boiling point of mercury, a mercury-in-glass thermometer is impracticable.
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