How is the rate of a cooling of a building affected by the thickness and the thermal conductivity of its walls?

How is the rate of a cooling of a building affected by the thickness and the thermal conductivity of its walls?
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Answer :

Generally thicker walls slow down the transfer of heat, and if the material is a good thermal conductor that will increase the rate of transfer.
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Walls of a cubical oven are of thickness l, and they are made of material of thermal conductivity k. The temperature inside the oven is 100°C and the inside heat transfer co-efficient is ‘3k/l’. If the wall temperature on the outside is held at 25°C, what is the inside wall temperature in degree centigrade?(A) 35.5 (B) 43.75 (C) 81.25 (D) 48.25

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