Module 1: Basic Concepts - Temperature - Answers

#1

Which of the following temperature scales are "relative" scales? Select all that apply.

: Answer: a and c; Celsius and Fahrenheit are relative temperature scales. The Celsius scale uses the freezing point of water as a reference point of 0°C. The boiling point of water at sea level is defined as 100°C. The Fahrenheit scale (British and American engineering usage) chooses 32°F for the freezing point of water and 212°F as the boiling point. These scales use numbers that are familiar to everyone. The Celsius and Fahrenheit temperature scales are termed "relative" temperature scales since the values are related to familiar occurrences, namely the freezing and boiling points of water.

Which of the following temperature scales are absolute scales? Select all that apply.

: Answer: b and d; Rankine and Kelvin are absolute temperature scales because they start at absolute zero. The freezing point of water expressed in these two temperature scales is 273°K or 492°R. Neither of the absolute temperature scales provides numbers that are familiar or in public use. For convenience, relative temperature scales have been developed.

#3

From Figure 1 [Temperature scales (Kelvin-Celsius)], what do you know about the size of a degree Kelvin compared to a degree Celsius?

: Answer: c. °K = °C; You know these two scales have equivalent degree sizes because both have a 100 degree difference between their respective freezing and boiling points for water (the two points shown on the diagram).

#4

From Figure 2 [Temperature scales (Rankine-Fahrenheit)], what do you know about the size of a degree Rankine compared to a degree Fahrenheit?

: Answer: c. °R = °F; You know these two scales have equivalent degree sizes because both have a 180 degree difference between their respective freezing and boiling points for water. (672°R - 492°R = 180°R and 212°F - 32°F = 180°F).

#5: From Figure 3 [Temperature scales (Kelvin-Celsius and Rankine-Fahrenheit)], when a gas temperature rises 150°F how much has it risen in degrees Rankine?

: Answer: 150°R; Because a degree Fahrenheit equals a degree Rankine, a change in degrees Fahrenheit results in an equivalent change in degrees Rankine. This relationship is true for the Celsius and Kelvin temperature scales as well. A temperature drop of 50°C equals a temperature drop of 50°K.

#6: Using Figure 3, can you figure out how to convert from °R to °F?; Hint: °R = °F + ?

: Answer: 460; The offset between the two scales is 460° since 0°F = 460°R.

#7: Using Figure 3, can you figure out how to convert from °K to °C?; Hint: °K = °C + ?

: Answer: 273; The offset between the two scales is 273° since 0°C = 273°K.