Two identical blocks of metal, one at 100°C and the other at 0°C, are brought into thermal contact. If no heat is lost to the surroundings, what will be the final temperature of the blocks?

Core Concept

Since the blocks are identical, they have the same heat capacity. When brought into thermal contact, heat will flow from the hotter block to the colder block until they reach thermal equilibrium. Because they have identical heat capacities, the final temperature will be the average of the initial temperatures: (100°C + 0°C)/2 = 50°C.