Chapter 19.2, Problem 1AE

Return to the Chapter-Opening Question, page 496, and answer it again now. Try to explain why you may have answered differently the first time.

 A 5-kg cube of warm iron (60°C) is put in thermal contact with a 10-kg cube of cold iron (15°C). Which statement is valid:

1. (a) Heal flows spontaneously from the warm cube to the cold cube until both cubes have the same heat content.
2. (b) Heat flows spontaneously from the warm cube to the cold cube until both cubes have the same temperature.
3. (c) Heat can flow spontaneously from the warm cube to the cold cube, but can also flow spontaneously from the cold cube to the warm cube.
4. (d) Heat can never flow from a cold object or area to a hot object or area.
5. (e) Heat flows from the larger cube to the smaller one because the larger one has more internal energy.