degrees Fahrenheit (F) to degrees Rankine (R) conversion

What is degrees Fahrenheit?

Degrees Fahrenheit ($^\circ F$) is a unit of temperature measurement commonly used in the United States and a few other countries. It's part of the Fahrenheit scale, a temperature scale developed by physicist Daniel Gabriel Fahrenheit in the early 18th century.

History and Origin

• Daniel Gabriel Fahrenheit: The scale is named after him, a German physicist, instrument maker, and glassblower.
• Early Thermometers: Fahrenheit made significant improvements to the accuracy and reliability of thermometers, which were still relatively new at the time.
• Original Zero Point: Fahrenheit originally defined 0 $^\circ F$ as the freezing temperature of a brine solution made from water, ice, and ammonium chloride salt.
• Water's Freezing Point: He initially set the freezing point of pure water at 32 $^\circ F$ and the human body temperature at 96 $^\circ F$ (later refined to 98.6 $^\circ F$).

Defining Points

The Fahrenheit scale is defined by two fixed points:

• Freezing Point of Water: 32 $^\circ F$
• Boiling Point of Water: 212 $^\circ F$ (at standard atmospheric pressure)

This means there are 180 degrees between the freezing and boiling points of water on the Fahrenheit scale.

Conversion Formulas

• Celsius to Fahrenheit:

  $^\circ F = (^\circ C * \frac{9}{5}) + 32$

• Fahrenheit to Celsius:

  $^\circ C = \frac{5}{9} (*^\circ F - 32)$

Real-World Examples

• Body Temperature: Normal human body temperature is approximately 98.6 $^\circ F$.
• Room Temperature: Comfortable room temperature is often around 72 $^\circ F$.
• Baking Temperatures: Many baking recipes use Fahrenheit, such as 350 $^\circ F$ for cakes or 400 $^\circ F$ for roasting vegetables.
• Weather Reports: In countries that use Fahrenheit, weather forecasts provide temperatures in degrees Fahrenheit. For example, a hot summer day might be 95 $^\circ F$, while a cold winter day could be 20 $^\circ F$.

Notable Facts

• Usage: While most countries use the Celsius scale for everyday temperature measurements, Fahrenheit remains common in the United States, the Bahamas, Belize, the Cayman Islands, and Liberia.

• Kelvin Scale Relationship: Although less direct than with Celsius, Fahrenheit can also be related to the Kelvin scale:

  $K = \frac{5}{9} (*^\circ F - 32) + 273.15$

What is degrees rankine?

Degrees Rankine ($^\circ R$) is a thermodynamic (absolute) temperature scale named after the Scottish physicist and engineer William John Macquorn Rankine, who proposed it in 1859. It's primarily used in engineering, particularly in the United States. Let's delve into its details.

Definition and Origin

The Rankine scale, like the Kelvin scale, is an absolute temperature scale, meaning its zero point (0 $^\circ R$) corresponds to absolute zero, the theoretical temperature at which all molecular motion ceases. The key difference is that the Rankine scale uses the Fahrenheit degree as its unit interval, whereas the Kelvin scale uses the Celsius degree.

Conversion Formulas

Here's how to convert between Rankine and other common temperature scales:

• Rankine to Fahrenheit:

  $^\circ R = ^\circ F + 459.67$

• Rankine to Celsius:

  $^\circ R = (^ \circ C + 273.15) \times \frac{9}{5}$

• Rankine to Kelvin:

  $^\circ R = K \times \frac{9}{5}$

The zero point of the Rankine scale is absolute zero, which is −459.67 $^\circ F$ or -273.15 $^\circ C$.

Historical Context and William Rankine

William John Macquorn Rankine (1820-1872) was a prominent Scottish engineer and physicist. He made significant contributions to thermodynamics, engine design, and soil mechanics. The Rankine cycle, a fundamental concept in thermodynamics describing the operation of heat engines, is also named after him. While he is known for the Rankine scale, his broader work in thermodynamics had a more lasting impact. He was the first to use the term "Thermodynamics"

Practical Applications and Examples

While not as widely used as Celsius, Fahrenheit, or Kelvin, the Rankine scale finds applications in specific engineering contexts, particularly in the United States, especially when dealing with thermodynamic calculations.

• Thermodynamics: In engineering thermodynamics, the Rankine scale is valuable when absolute temperature values are needed, simplifying calculations involving energy transfer and thermodynamic processes.
• Combustion: When analyzing combustion processes, using absolute temperature scales like Rankine avoids potential issues with negative temperature values in calculations.
• Aviation: Although less common now, some older engineering practices in aviation might have utilized Rankine for certain calculations related to engine performance or atmospheric conditions.

Examples of approximate Rankine values for common temperatures:

• Freezing point of water: 491.67 $^\circ R$
• Boiling point of water: 671.67 $^\circ R$
• Standard room temperature (25 $^\circ C$ or 77 $^\circ F$): 536.67 $^\circ R$

Advantages and Disadvantages

Advantages:

• It is an absolute temperature scale, which is useful in thermodynamic calculations.
• It uses the Fahrenheit degree, which is familiar to engineers in the United States.

Disadvantages:

• It is not as widely used as Celsius, Fahrenheit, or Kelvin.
• The Fahrenheit degree is smaller than the Celsius degree, which can make calculations more difficult.

Further Reading

For a deeper understanding, consider exploring these resources:

• Thermodynamic temperature - Wikipedia