Alfred Martin

2021-12-16

A picture window has dimensions of and is made of glass 5.20 mm thick. On a winter day, the temperature of the outside surface of the glass is $-{20.0}^{\circ }$C, while the temperature of the inside surface is a comfortable ${19.5}^{\circ }$ C. (a) At what rate is heat being lost through the window by conduction? (b) At what rate would heat be lost through the window if you covered it with a 0.750-mm-thick layer of paper (thermal conductivity $0.0500\frac{w}{m}\cdot k$

Debbie Moore

We can calcualte the thermal resistance via
$R=\frac{L}{K}$

$=6.5×{10}^{-3}\frac{{m}^{2}}{\cdot }\frac{K}{W}$
The rate of heat loss can be determined from
$H=\frac{A}{R}\left[{T}_{H}-{T}_{C}\right]$

Bertha Jordan

b. ,
After converting the window with paper there will be additional thermal resistance
${R}_{t}={R}_{glass}+{R}_{paper}$
for ${R}_{paper}$
${R}_{paper}=\frac{L}{K}$

${R}_{t}=0.015+6.5×{10}^{-3}$

To calculated the rate of heat loss, calculate ${R}_{task}$
$H=\frac{A}{R}\left[{T}_{H}-{T}_{C}\right]$

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