Study Notes on Heat and Temperature

Heat and Temperature

Absolute Temperature

• Definition of Absolute Temperature:
  • Absolute temperature is the point at which all molecular motion ceases in a body.
  • At this point, the body has absolutely no heat left.
• Absolute Zero:
  • The lowest possible temperature.
  • Value: Approximately -273°C or -460°F.

Temperature Scales

• Kelvin Scale:
  • Also known as Celsius Absolute.
  • Used primarily in scientific, engineering, and manufacturing applications.
  • No degree symbol is used with Kelvin temperatures, represented with the letter 'K'.
  • Example: 200 degrees Kelvin is written as 200 K.
• Rankine Scale:
  • Also known as Fahrenheit Absolute.
  • This scale was replaced by the Kelvin scale.
  • Absolute temperature in degrees Rankine is derived by adding 460 degrees to the Fahrenheit temperature.

Conversion between Temperature Scales

• Celsius to Kelvin:

  • Formula:
  • $K = °C + 273$
  • Example: What is 10°C in kelvins?
  • Solution:
    • $K = 10°C + 273$
    • $K = 283$
  • Thus, 10°C equals 283 K.

• Kelvin to Celsius:

  • Formula:
  • $°C = K - 273$
  • Example: What is 300 K in degrees Celsius?
  • Solution:
    • $°C = 300K - 273$
    • $°C = 27$
  • Thus, 300 K is equal to 27°C.

Standard Points of Temperature

• Boiling Point of Water:
  • In Celsius: 100°C
  • In Kelvin: 373 K
  • In Fahrenheit: 212°F
• Freezing Point of Water:
  • In Celsius: 0°C
  • In Kelvin: 273 K
  • In Fahrenheit: 32°F
• Absolute Zero:
  • In Celsius: -273°C
  • In Kelvin: 0 K
  • In Fahrenheit: -460°F

Conversion Methodology

• Note that there is no direct way to convert between two temperature scales.
  • To convert from kelvins to degrees Fahrenheit:
  1. First, convert kelvins to degrees Celsius.
  2. Then convert from Celsius to Fahrenheit.

Summary of Important Conversions