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Question #42552
The Question
A cylinder contains moles of an ideal monatomic gas. A piston of mass and cross-sectional area is attached to a spring of constant and a damper. The damper exerts a non-linear drag force on the piston, where is its velocity and is a positive constant. The gas undergoes a forced thermodynamic cycle such that the piston's state traces an ellipse in phase space given by , where is the displacement from equilibrium and is the momentum. At the state of maximum momentum, the piston's kinetic energy equals the internal energy that moles of this gas would have at a reference temperature . Assuming the external pressure is zero, what is the net heat absorbed by the gas per cycle?
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Intuition_Breaker
Train your brain to resist "obvious" answers that are designed to deceive your intuition.
Concepts Behind This Question
Cyclic Process Geometry|Phase Space Trajectory|Equipartition Theorem
Why This Question Is Tricky
Common Mistakes
The question tests the student's ability to apply the First Law of Thermodynamics to a non-ideal, dissipative mechanical coupling.
A common trap is assuming that the cyclic integral of work is simply the area of the phase space trajectory or zero for a conservative-looking spring system.
Students often fail to recognize that the gas must perform net positive work to continuously overcome the non-linear viscous damping (), meaning the area equals the irreversible energy dissipated per cycle.
Furthermore, it integrates the Equipartition Theorem to establish the momentum amplitude, punishing students who cannot link microscopic thermodynamic states to macroscopic phase space parameters.
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 |