A student arranges two blocks of copper next to each other so that they are touching. At the start of the experiment, Block 1’s temperature is 40°C, and Block 2’s temperature is 20°C. The two blocks remain in an isolated system until all heat energy is transferred. Which picture correctly shows the blocks’ ending temperatures? (1 point)

A. 30°C 30°C
Block 1 Block 2

B. 70°C 70°C
Block 1 Block 2

C. 50°C 20°C
Block 1 Block 2

D. 20°C 50°C
Block 1 Block 2

1 answer

In an isolated system where two blocks of copper are in contact, heat will flow from the hotter block to the cooler block until thermal equilibrium is reached.

In this case:

  • Block 1 starts at 40°C.
  • Block 2 starts at 20°C.

Since there are two blocks, when they reach thermal equilibrium, the final temperature of both blocks will be the average of their initial temperatures.

To find the ending temperature: \[ \text{Final Temperature} = \frac{\text{Temperature of Block 1} + \text{Temperature of Block 2}}{2} = \frac{40°C + 20°C}{2} = \frac{60°C}{2} = 30°C \]

Thus, both blocks will end up at 30°C.

The correct choice showing the ending temperatures is:

A. 30°C 30°C Block 1 Block 2