Block A consists of 400 grams of copper. It is placed in thermal contact with Bl
ID: 3161787 • Letter: B
Question
Block A consists of 400 grams of copper. It is placed in thermal contact with Block B, consisting of 100 grams of copper. The graph at left shows the entropy of Block At the entropy of Block B, and the total entropy of both blocks, as a function of the percentage of the total energy of the system found in block A. block B block A block A block B 100 50 Energy in block A (s of total energy) After the system has reached equilibrium, what is the most probable fraction of the total energy found in block A? Explain how you can tell this from the graph.Explanation / Answer
According to Second law of thermodynamics, if a system is not in equillibrium, then the most probable consequence is that the entropy of the system will increase - in other words the system will tends towards maximum entropy.
At equillibrium, the maximum entropy will corresponds to the most probable fraction of the total enery found in any of the block.
From the graph, this value can be calculated by drawing a vertical from the peak of the block A + block B curve.
This value will be close to 80% for block A.
Hence at equillibrium, most probable fraction of total energy found in A will be 80% and that in B will be 20%.