Physics

Problem

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

10\,\text{m}^2

: • Layer A: brick of thickness

0.10\,\text{m}

and thermal conductivity

0.80\,\text{W}\!\big/\!(\text{m}\cdot\text{K})

• Layer B: foam insulation of thickness

0.050\,\text{m}

and thermal conductivity

0.040\,\text{W}\!\big/\!(\text{m}\cdot\text{K})

The indoor surface is held at

25\,^{\circ}\!\text{C}

, and the outdoor surface stays at

0\,^{\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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