Thermodynamic scale in the S.I. system: select the correct unit of temperature used internationally for scientific and engineering work.
Civil Engineering
SI Units
Difficulty: Easy
Choose an option
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ADegree centigrade
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BDegree Celsius
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CKelvin
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DDegree Fahrenheit
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ERankine
Answer
Correct Answer: Kelvin
Explanation
Introduction / Context:Temperature scales appear everywhere in engineering: material properties, gas laws, and heat-transfer calculations. The S.I. chooses a single coherent base unit for thermodynamic temperature to ensure universal comparability and to avoid offsets that complicate equations.
Given Data / Assumptions:
- The S.I. base unit for thermodynamic temperature is the kelvin (K).
- Informal terms like “degree centigrade” are deprecated; “degree Celsius” (°C) remains widely used for everyday measurements but is not the S.I. base unit.
- Fahrenheit and Rankine are non-S.I.
Concept / Approach:Many formulas (e.g., ideal gas law) require an absolute scale without arbitrary zero points; the kelvin provides this. While Celsius is convenient for weather or lab readings, kelvin is the fundamental unit in S.I.-based computations and standards.
Step-by-Step Solution:
Identify S.I. base unit: kelvin (symbol K).Note relationship: T[K] = t[°C] + 273.15.Therefore, the correct choice is Kelvin.Verification / Alternative check:
Check S.I. brochure: thermodynamic temperature base unit is kelvin, not degree-based units.Why Other Options Are Wrong:
Degree centigrade: obsolete term for Celsius.Degree Celsius: practical unit, but not the S.I. base unit.Degree Fahrenheit, Rankine: non-S.I. scales.Common Pitfalls:
Confusing everyday measurement units with S.I. base units.Using °C directly in absolute-temperature formulas that require kelvin.Final Answer:
Kelvin