Rankine Conversion (ºR)

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Wordwide use:

Rankine is a unit of measurement used to quantify temperature. While it is not as widely used as other temperature scales such as Celsius or Fahrenheit, it still finds some applications in certain fields and regions around the world. The Rankine scale is primarily used in engineering and thermodynamics, particularly in the United States.

In the field of engineering, Rankine is often used in the analysis and design of power plants, refrigeration systems, and other industrial processes. It is particularly useful in these applications because it directly relates temperature to energy, making calculations and conversions more straightforward. Additionally, the Rankine scale is commonly used in the study of combustion processes and gas dynamics.

Outside of the United States, the use of Rankine is less prevalent. Most countries, especially those that have adopted the metric system, tend to use Celsius or Kelvin as their primary temperature scales. However, it is worth noting that some countries, such as the United Kingdom, still use the Rankine scale in certain specialized fields like aviation and aerospace engineering.


The Rankine is a unit of temperature in the absolute temperature scale, commonly used in engineering and thermodynamics. The Rankine scale is based on the Fahrenheit scale, with zero Rankine being absolute zero, the point at which all molecular motion ceases.

The Rankine scale is often used in conjunction with the Kelvin scale, which is the primary unit of temperature in the International System of Units (SI). The Rankine scale is defined by the equation Rankine = Fahrenheit + 459.67. This means that the size of one degree Rankine is equal to the size of one degree Fahrenheit. However, unlike the Fahrenheit scale, which has its zero point at an arbitrary value, the Rankine scale has its zero point at absolute zero, making it an absolute temperature scale.


The Rankine scale is a temperature scale named after the Scottish engineer and physicist William John Macquorn Rankine. Born in 1820, Rankine made significant contributions to the field of thermodynamics and engineering. He is best known for his work on the theory of heat engines and the development of the Rankine cycle, which is widely used in power plants.

Common references:

Absolute Zero, 0ºR

Melting point of ice, 491.67ºR

Warm summer's day in a temperate climate, 531ºR

Normal human body temperature, 558.27ºR

Boiling point of water at 1 atmosphere, 671.67ºR

Usage context:

The Rankine scale is primarily used in the field of thermodynamics, particularly in the analysis of heat engines and power cycles. It is often used in conjunction with the Kelvin scale, which is the standard unit of temperature in the scientific community. The Rankine scale is particularly useful in engineering applications where temperature differentials and energy transfers are important, such as in the design and analysis of steam power plants, refrigeration systems, and gas turbines.

In addition to its usage in thermodynamics, the Rankine scale is also occasionally used in some specialized fields, such as aerospace engineering and materials science. In these contexts, the Rankine scale may be used to measure extreme temperatures or temperature gradients, where the Fahrenheit or Celsius scales may not provide sufficient precision or range. However, it is important to note that the Rankine scale is not commonly used in everyday life or in most scientific disciplines outside of thermodynamics.

What happens at absolute zero (0K)?:

At absolute zero, also known as 0 Kelvin (0K) or -273.15 degrees Celsius, the temperature is at its lowest possible point. At this extreme temperature, the kinetic energy of atoms and molecules reaches its minimum, causing them to come to a complete standstill. As a result, all molecular motion ceases, and matter becomes as still as it can be.

At this temperature, several fascinating phenomena occur. One of the most notable is the complete absence of heat energy. As there is no molecular motion, there is no transfer of heat from one object to another. This absence of heat energy has significant implications for various physical properties. For instance, materials become extremely brittle, and their electrical resistance drops to zero. Additionally, gases condense into liquids, and liquids freeze into solids, as the lack of molecular motion prevents them from maintaining their fluid state.

Scientists have never been able to achieve absolute zero in practice, as it is an idealized concept. However, by cooling substances to extremely low temperatures, they have been able to observe and study the effects of approaching absolute zero. These experiments have provided valuable insights into the behavior of matter and have led to the development of technologies such as superconductors and Bose-Einstein condensates.

Why can't you go below ºR?:

The Rankine (ºR) is a unit of temperature measurement in the Imperial system, primarily used in engineering and thermodynamics. It is closely related to the Kelvin (K) scale in the metric system, with the same size of degree. Like the Kelvin scale, the Rankine scale starts at absolute zero (0 ºR) but uses the Fahrenheit degree size.

The reason why you cannot go below 0 ºR on the Rankine scale is because it represents absolute zero, the lowest possible temperature in the universe. Absolute zero is defined as the point at which all molecular motion ceases, and no further decrease in temperature is possible. At this temperature, all substances would have no thermal energy and would be in a state of complete rest.

Attempting to go below 0 ºR would imply going below absolute zero, which is not physically possible. It would violate the laws of thermodynamics and contradict our understanding of the behaviour of matter. Therefore, the Rankine scale, like the Kelvin scale, has its lower limit fixed at absolute zero, ensuring that no temperatures below this point can be measured or expressed.


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