Question

Use the worked example above to help you solve this problem. Find the energy transferred in 1 h by conduction through a concrete wall 1.6 m high, 4.00 m long, and 0.20 m thick if one side of the wall is held at 20°C and the other side is at 5°C.

Answer 1

The energy transferred is 2.93 MJ.

Step-by-step explanation:

Given that,

Time = 1 h = 3600 s

Area
`A = 1.6*4.00`

Width
`\Delta x=0.20 m`

Temperature
`T_(1)=20^(\circ)\ C`

`T_(2)=5^(\circ)\ C`

For concrete wall,

The thermal conductivity

k = 1.7 W/mK

Using Fourier's law

`Q=kA(dt)/(\Delta x)`

Where, A = area

`\Delta x` = width

`\Delta t` = change in temperature

k = thermal conductivity

Put the value into the formula

`Q=1.7* 1.6* 4.00*(15)/(0.20)`

`Q=816\ W`

The energy transferred in 1 hour

`E = Q* t`

`E=816*3600`

`E=2937600`

`E = 2.93*10^(6)\ J`

`E = 2.93\ MJ`

Hence, The energy transferred is 2.93 MJ.