Question

two solid blocks are heated to the temperatures shown. the blocks are placed so they touch. which diagram shows the direction heat will flow?

Explanation:

Step1: Recall heat - flow principle

Heat flows from a region of higher temperature to a region of lower temperature. When two objects are in contact and have the same temperature, there is no heat flow between them.

Step2: Analyze the given diagrams

In the first diagram, it is labeled "NO HEAT FLOW" and both blocks are at 0°C. Since there is no temperature difference, this is correct. In the second and third diagrams, there is a heat - flow arrow shown between the two blocks which are both at 0°C. This is incorrect because for heat to flow, there must be a temperature difference.

Answer:

The first diagram (the one labeled "NO HEAT FLOW") correctly represents the situation as there is no heat flow when the two blocks are at the same temperature.