question_answer 3)

Explain why (a) Two bodies at different temperatures  and , if brought in thermal contact do not necessarily settle to the mean temperature   (b) The coolant in a chemical or nuclear plant (i.e., the liquid used to prevent different parts of a plant from getting too hot) should have high specific heat. Comment. (c) Air pressure in a car tyre increases during driving. Why ? (d) The climate of a harbour town is more temperate (i.e., without extremes of heat and cold) than that of a town in a desert at the same latitude. Why ?  

Answer:

(a) 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 only when      thermal capacities of the two bodies are equal. (b) This is because heat absorbed by a substance is directly proportional to the specific heat of the substance. (c) During driving, the temperature of air inside the tyre increases due to motion. According to Charle's law, . Therefore, air pressure inside the tyre increases. (d) This is because in a harbour town, the relative humidity is more than in a desert town. Hence, the climate of a harbour town is without extremes of hot and cold.