Home » Mechanical Engineering » Thermodynamics

Gas constants: select the correct SI value for the specific gas constant of air Pick the correct numerical value (with units) commonly used for the gas constant of air in SI calculations. Choose the correct option.

Q: Gas constants: select the correct SI value for the specific gas constant of air Pick the correct numerical value (with units) commonly used for the gas constant of air in SI calculations. Choose the correct option.

Concept The specific gas constant for air is Rair ≈ 287 J/(kg·K). (The universal gas constant is 8.314 kJ/(kmol·K) = 8314 J/(kmol·K).) Final Answer 287 J/kg·K

Difficulty: Easy

0.287 J/kg·K
2.87 J/kg·K
28.7 J/kg·K
287 J/kg·K

Correct Answer: 287 J/kg·K

Explanation:

Concept
The specific gas constant for air is R_air ≈ 287 J/(kg·K). (The universal gas constant is 8.314 kJ/(kmol·K) = 8314 J/(kmol·K).)

Final Answer
287 J/kg·K

← Previous Question Next Question→

More Questions from Thermodynamics

Town (street/domestic) lighting/heating gas — historical usage Identify which manufactured gas was mostly used historically for street and domestic lighting and heating in towns. Choose the correct option.
Temperature scales: absolute zero reference on Celsius and Fahrenheit scales Select the correct value that represents absolute zero temperature. Choose the correct option.
Properties of water: standard specific heat value (approximate) Choose the standard textbook value for the specific heat of liquid water near room temperature. Choose the correct option.
Petroleum processing: identify the separation method described Process description: evaporate and condense the component with the lowest boiling point first, then the next higher, and so on, recovering liquid fuels separately in order of boiling point. Choose the correct process name.
Thermal engineering (fuels): identify the incorrect statement about fuels Options compare properties of liquid and solid fuels and desirable fuel characteristics. Choose the single incorrect statement from the list.
Fluid mechanics basics: select the correct pressure relation Definitions: Absolute pressure, Gauge pressure, Atmospheric pressure. Choose the correct equation relating these three.
Thermodynamics: work in a free expansion process A gas expands freely against vacuum (no external resistance) from one volume to a larger volume. What is the work done by the gas in free expansion?
Reversibility of basic thermodynamic processes: evaluate the statement Statement: “The constant-pressure, constant-volume, and general p·vⁿ processes are regarded as irreversible processes.” Decide whether this statement is correct.
Fuels: name the process—coal strongly heated for 42–48 hours in a closed vessel without air Identify the standard term for this process used to produce coke and by-products.
First law at constant volume: decide correctness of the statement Statement: “When a gas is heated at constant volume, the heat supplied increases the internal energy of the gas.”

Discussion & Comments

No comments yet. Be the first to comment!

Join Discussion