9.1: The concrete roof of a house of thickness 20 cm has an area 200 m². The temperature inside the house is 15°C and outside is 35°C. Find the rate at which thermal energy will be conducted through the roof. The value of k for concrete is 0.65 Wm⁻¹K⁻¹. Ans. (13000 Js⁻¹)

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9.2: How much heat is lost in an hour through a glass window measuring 2.0 m by 2.5 m when inside temperature is 25°C and that of outside is 5°C, the thickness of glass is 0.8 cm and the value of k for glass is 0.8Wm⁻¹K⁻¹? Ans. (3.6x10⁷J)