Question

At what rate (J/s) is heat lost through a 80 cm by 60 cm glass window pane that is 5.0mm thick when the inside temperature is 20°C and the outside temperature is 2°C.

Answer 1

We will have the following:

First, we remember that thermal conductivity is given by:

$Q(t)=|\frac{k\cdot A\cdot(T_h-T_c)}{d}|$

So, we replace the values and solve, that is:

$Q(t)=|\frac{(0.80J/s\cdot m\cdot C)(0.8m\cdot0.6m)(20C-2C)}{0.005m}|\Rightarrow Q(t)=|\frac{6.912J\cdot m/s}{0.005m}|$$\Rightarrow Q(t)=|1382.4J/s|$

So, the rate is 1382.4 Joules per second.