Kelvin temperature conversion from Celsius

A degree is both a temperature and a temperature interval, a fact that sometimes leads to confusion. Consider the temperature interval from 0°C to 5°C. There are nine Fahrenheit and nine Rankine degrees in this interval, and only five Celsius degrees and five Kelvin. An interval of 1 Celsius degree or Kelvin therefore contains 1.8 Fahrenheit or Rankine degrees, leading to the conversion factors... 

So if a gas is heated by 1 °C, its volume increased by 1/273 of its volume at 0 °C. (The 273 comes from the conversion of Celsius to Kelvin.) The opposite is also true if the temperature is decreased by 1 °C, then the volume decreases by 1/273. In theory, at absolute zero (—273 °C) the volume of a gas is 0 dm, but real gases turn into liquids before this point. 

Three systems for measuring temperature are widely used the Celsius scale, the Kelvin scale, and the Fahrenheit scale. The first two temperature systems are used in the physical sciences, and the third is used in many of the engineering sciences. Our purpose here is to define the three temperature scales and show how conversions from one scale to another can be performed. Although these conversions can be carried out routinely on most calculators, we will consider the process in some detail here to illustrate methods of problem solving. 

Scientific uses of temperature require yet another temperature scale. The choice of the kelvin as the standard reflects mathematical convenience more than familiarity. The Kelvin scale is similar to the Celsius scale but draws its utility from the fact that the lowest temperature theoretically possible is zero kelvin. It violates the laws of namre to go below 0 K, as we will see in Chapter 10. The mathematical importance of this definition is that we are assured we will not divide by zero when we use a formula that has temperamre in the denominator of an expression. Conversions between Celsius degrees and kelvins are common in science and are also more straightforward. 

Kelvin (1848) introduced a temperature scale having the same size degree as tire Celsius degree, but with zero at the point where all vibrational motion ceases and the pressure of a gas is zero. Zero temperature on the Kelvin (absolute) scale is -273°C=-460°F. This is a more useful scale than the Celsius scale for scientific purposes since the amplitude of molecular vibration is approximately proportional to the absolute temperature (°K). Conversion from °C to °K is as follows ... 

This definition ensures that temperature intervals in the kelvin scale are identical with the temperature intervals in the Celsius scale. Thus, conversion from thermodynamic temperature T to Celsius temperature 6 is ... 

Still other units encountered in the literature and workplace come from various other systems (absolute and otherwise). These include metric systems (c.g.s. and MKS), some of whose units overlap with SI units, and those (FPS) based on English units. The Fahrenheit and Rankine temperature scales correspond to the Celsius and Kelvin, respectively. We do not use these other units, but some conversion factors are given in Appendix A. Regardless of the units specified initially, our approach is to convert the input to SI units where necessary, to do the calculations in SI units, and to convert the output to whatever units are desired. 

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