Question

The brick wall of thermal conductivity0.75 W/m ° C) of a building has dimensionsof 2.7 m by 11 m and is 7 cm thick. How much heat flows through the wall ina 17.5 h period when the average inside andoutside temperatures are, respectively, 30°Cand 7°C?Answer in units of MJ.

Answer 1

`461.09MJ`

Step-by-step explanation

To find the amount of heat flow, we have to apply the equation for conduction rate through a wall:

`E=(k\cdot A\cdot\Delta T\cdot t)/(L)`

where k = thermal conductivity of the material

A = area of surface

ΔT = T₂ - T₁ = Outer temperature - inner temperature

t = amount of time (in seconds)

L = thickness of wall

From the question, we have that:

Therefore, the amount of heat that flows through the wall is:

`\begin{gathered} E=(0.75\cdot29.7\cdot23\cdot63000)/(0.07) \\ E=461,092,500J \\ E=461.09MJ \end{gathered}`