Question

Two iron blocks of equal size and mass are kept in contact with each other as shown in the figure. The block on the left side has been heated to 120°C and placed in contact with the block on the right side which has been cooled to 20°C. What are the temperatures of the two blocks once they have reached thermal equilibrium?

What are the final temperatures of the two blocks in Celsius?
a) 70°C
b) 70K
c) 120°C
d) 20°C

Answer 1

The final temperatures of two iron blocks of equal size and mass, one heated to 120°C and the other to 20°C, once they have reached thermal equilibrium, will be 70°C for both blocks. Therefore correct option is A

Step-by-step explanation:

When the two iron blocks of equal size and mass, one heated to 120°C and the other cooled to 20°C, reach thermal equilibrium, their final temperatures will be the same due to the zeroth law of thermodynamics, which states that if two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.

Since the mass and material of the blocks are the same, they will reach an equal intermediate temperature when heat transfer between them stops.

The average of the initial temperatures, (120°C + 20°C)/2, gives us the final equilibrium temperature of 70°C for both blocks. Therefore, the correct answer to the student's question is option a) 70°C.