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Question #41989
The Question
An ideal monatomic gas of molar mass undergoes a cyclic process. During the high-pressure isothermal expansion phase at temperature , the volume increases from to at a constant volumetric rate . Simultaneously, a microscopic valve of area is opened, allowing gas to effuse into a vacuum. The valve is closed during the rest of the cycle. If the effusion rate is given by , what is the ratio of the work done by the gas during this expansion phase to the work that would have been done if the valve remained closed? (Let )
Options
- A.
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- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Variable_Constraint
Develop pure symbolic logic skills by mastering algebraic constraints without relying on numerical data.
Concepts Behind This Question
Cyclic Process Geometry|Effusion and Diffusion|First Law Application
Why This Question Is Tricky
Common Mistakes
This question tests the student's ability to handle open thermodynamic systems where the number of moles is not a state constant but a path-dependent variable.
A common trap is treating as a constant or using an average value when calculating the work integral.
By coupling Graham's law of effusion with the macroscopic ideal gas law, the problem forces the setup of a first-order differential equation to find .
Failing to substitute this continuously varying into the work integral leads to incorrect logarithmic or linear approximations, exposing a fundamental misunderstanding of variable-mass thermodynamics.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Thermodynamics - Class 11 Part 2 |
| Concept | Cyclic Process Geometry |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |