Physics

Problem

A wall consists of a

10\,\text{cm}

layer of brick (

k_1=0.6\,\text{W\,m}^{-1}\text{K}^{-1}

) and a

2\,\text{cm}

layer of polystyrene (

k_2=0.04\,\text{W\,m}^{-1}\text{K}^{-1}

) in series. The area of the wall section is

1\,\text{m}^2

. If the room temperature is

30^{\circ}\text{C}

and the outside temperature is

10^{\circ}\text{C}

, the steady heat current through this section is closest to a)

40\,\text{W}

100\,\text{W}

30\,\text{W}

12\,\text{W}