A composite exterior wall consists of two flat layers in thermal contact over an area…

PHYSICS · Single correct · CBSE · Physics · Thermal Properties of Matter · Thermal Properties of Matter

Problem

A composite exterior wall consists of two flat layers in thermal contact over an area of 10 m210\,\text{m}^2: • Layer A: brick of thickness 0.10 m0.10\,\text{m} and thermal conductivity 0.80 W ⁣/ ⁣(m⋅K)0.80\,\text{W}\!\big/\!(\text{m}\cdot\text{K}) • Layer B: foam insulation of thickness 0.050 m0.050\,\text{m} and thermal conductivity 0.040 W ⁣/ ⁣(m⋅K)0.040\,\text{W}\!\big/\!(\text{m}\cdot\text{K}) The indoor surface is held at 25 ∘ ⁣C25\,^{\circ}\!\text{C}, and the outdoor surface stays at 0 ∘ ⁣C0\,^{\circ}\!\text{C} for 5 hours. Assuming steady-state one-dimensional conduction, what is the total energy conducted through the wall during this period? (a) 33 MJ (b) 0.33 MJ (c) 3.3 MJ (d) 18 MJ

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