Chapter 30, Problem 22A

To determine

To state: The term or law used to describe energy transfer from cooler location to warmer location by doing work.

Explanation of Solution

Introduction:

When a hot body is bought in contact with a cold body, heat energy transfers always from a hotter body to a colder one such that both the bodies may attain a state of thermal equilibrium i.e. they are at a constant temperature. However, if we want the heat to be moved back i.e. transfer of heat energy from a cold body to a hot body, work is required to be done by an external source.

The second law of thermodynamics states that energy can be spontaneously transferred from a higher concentration to a lower concentration i.e. from a hotter body to a cooler body. It is possible to do the reverse back of energy transfer i.e. to transfer energy from a lower concentration to a higher concentration but that cannot be happened spontaneously, it needs a work to be done on the system by an external source.

Conclusion:

The second law of thermodynamics states that thermal energy can be transferred from a cooler location to a warmer location only when work is done.