Below Figure shows graphs of entropy vs. energy for two objects, A and B. Both graphs are on the same scale. The energies of these two objects initially have the values indicated; the objects are then brought into thermal contact with each other. Explain what happens subsequently and why, without using the word “temperature.”
Figure: Graphs of entropy vs. energy for two objects.
We know the very fundamental definition of entropy, which is,
The inverse of temperature is the rate of change of entropy w.r.t internal energy.
This is true when there is no work done on or by the system.