A rigid container is divided into two equal-volume compartments by a thin partition
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
A rigid container is divided into two equal-volume compartments by a thin partition. Compartment L contains helium gas at temperature 400K and pressure 2.0×105Pa. Compartment R contains the same gas at temperature 300K and the same pressure of 2.0×105Pa. At time t=0 the partition is suddenly removed, and the gas is allowed to evolve toward a new equilibrium. The container is thermally insulated from its surroundings, and external pressure does no work on the system.
(a) Describe qualitatively how the pressures in the regions originally labeled L and R change immediately after the partition is removed and during the subsequent approach to equilibrium.
(b) Identify and justify the final value of the pressure throughout the container relative to the initial pressures.
(c) Using the concept of molecular speed distributions, explain why the final pressure is spatially uniform even though the temperatures in different regions may not have fully equalized.
(d) Must the average molecular kinetic energy in the gas that originated from compartment L equal that of the gas that originated from compartment R once equilibrium in pressure is achieved? Provide a reasoned justification for your answer.