Question

two identical blocks are heated to different temperatures. the blocks are placed so that they touch, and heat begins to flow between the blocks. the pair of blocks is insulated, so no energy escapes. later, the temperature of each block is measured again. which pair of temperatures is possible?

Explanation:

Step1: Understand heat - transfer principle

Heat flows from a hotter object to a colder object until thermal equilibrium is reached. In an insulated system, the total heat content remains the same. The temperature of the hotter block will decrease and the temperature of the colder block will increase.

Step2: Analyze each option

• Option 1: Block 1 remains at 75°C, which is incorrect as heat should flow from it to Block 2 and its temperature should decrease.
• Option 2: Block 1 has a lower temperature (55°C) and Block 2 has a higher temperature (69°C) after heat - transfer, which is incorrect as heat should flow from the initially hotter Block 1 to Block 2.
• Option 3: Block 1 has decreased in temperature from 75°C to 72°C and Block 2 has increased in temperature from 49°C to 52°C, which is consistent with the heat - transfer principle.
• Option 4: Block 2 has a lower temperature (42°C) after heat - transfer, which is incorrect as its temperature should increase.

Answer:

The pair of temperatures 72°C for Block 1 and 52°C for Block 2 is possible.