Question

the system at left has the divider removed. which image represents this system in thermal equilibrium?

Explanation:

Step1: Recall thermal equilibrium concept

In thermal equilibrium, heat is transferred until temperatures are equal. Here, the combined system will reach a common temperature. Since heat flows from high - temperature (100K) to low - temperature (50K) regions. The final state should have a uniform temperature.

Step2: Analyze each option

• Option 1: Still has distinct 50K and 100K regions. Not in equilibrium.
• Option 2: All particles at 75K (average of 50K and 100K in a sense of thermal equilibrium when heat transfer occurs until uniform temperature). This represents thermal equilibrium.
• Option 3: Still has distinct 50K and 100K regions. Not in equilibrium.

Answer:

The second image (with all particles at 75K) represents the system in thermal equilibrium.