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Explain why Two bodies at different temperatures T_{1} and T_{2}, if brought in thermal contact, do not necessarily settle to the mean temperature (T_{1} + T_{2})/2.

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#### Solution 1

When two bodies at different temperatures *T*_{1} and* T*_{2} are brought in thermal contact, heat flows from the body at the higher temperature to the body at the lower temperature till equilibrium is achieved, i.e., the temperatures of both the bodies become equal. The equilibrium temperature is equal to the mean temperature (*T*_{1} + *T*_{2})/2 only when the thermal capacities of both the bodies are equal.

#### Solution 2

In thermal contact, heat flows from the body at higher temperature to the body at lower temperature till temperatures become equal. The final temperature can be the mean temperature (T_{1}+ T_{2})/2 only when thermal capacities of the two bodies are equal.

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