The ceiling of a cold storage room has an area of

PHYSICS · Multi-part · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

The ceiling of a cold storage room has an area of 4.0 m24.0\,\text{m}^2. The temperature difference between the inner and outer surfaces is expected to remain about 25 K25\,\text{K}. The heat gain through the ceiling must not exceed 80 W80\,\text{W}. Three insulating boards are available: Board A: k=0.040 W m−1 K−1k = 0.040\,\text{W m}^{-1}\,\text{K}^{-1} Board B: k=0.060 W m−1 K−1k = 0.060\,\text{W m}^{-1}\,\text{K}^{-1} Board C: k=0.080 W m−1 K−1k = 0.080\,\text{W m}^{-1}\,\text{K}^{-1} (i) For each board, calculate the maximum permissible thickness that will satisfy the heat-gain limit. (ii) Which board allows the thinnest ceiling? State its required thickness.

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