Start Learning Free

Before You Begin

Question #42191

Difficulty: 8/10 | 🟢 Free

The Question

A vertical cylindrical container with adiabatic walls contains nn moles of a monatomic ideal gas. It is fitted with a frictionless, adiabatic piston of mass MM and cross-sectional area AA. The atmospheric pressure is P0P_0, and it is given that P0=MgAP_0 = \frac{Mg}{A}. Initially, the container is placed in an elevator accelerating upwards with an acceleration a=ga = g (where gg is the acceleration due to gravity). The gas is in thermal and mechanical equilibrium with an initial volume V0V_0. Suddenly, the elevator's acceleration drops to zero and it continues to move with a constant upward velocity. The gas expands and eventually reaches a new equilibrium state with volume VfV_f. Find the ratio VfV0\frac{V_f}{V_0}.

Options

  • A.

    1310\frac{13}{10}

  • B.

    (32)3/5\left(\frac{3}{2}\right)^{3/5}

  • C.

    115\frac{11}{5}

  • D.

    54\frac{5}{4}

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

Adiabatic Process Constraint|Frame of Reference|Newton’s Laws

Why This Question Is Tricky

Common Mistakes

This question tests the student's ability to distinguish between reversible and irreversible adiabatic processes in a non-inertial frame.

The trap lies in blindly applying the standard reversible adiabatic equation (PVγ=constantPV^\gamma = \text{constant}) when the external pressure changes abruptly due to a sudden change in the frame's acceleration.

The sudden change in the pseudo-force alters the effective weight of the piston, making the expansion irreversible against a new, constant external pressure.

Students who fail to recognize this will incorrectly use the reversible relation, ignoring that the boundary work term W=∫PextdVW = \int P_{ext} dV is governed by the modified non-inertial constraint.

Quick Facts About This Question

Question Information

SubjectPhysics
ChapterThermodynamics - Class 11 Part 2
ConceptAdiabatic Process Constraint
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree