A cubical box 22cm on a side is constructed from 1.3cm -thick concrete panels. A 100 W lightbulb is sealed inside the box. What is the air temperature inside the box when the light is on if the surrounding air temperature is 20 C?
rate of heat transfer : heat / delta small t = (k*A*delta big T)/ L
Where : k = characterizes the material : (in this case its concrete) : 0.8 W/m K
L = Thickness of the panels : .013m
A = cross-section area = s^2 : (.22m)^2 = .0484
The Attempt at a Solution
100 W = ((0.8)(.22)^2(Tin - 20 C)) / .013m // the 20 C is the Tout
Tin = 53.5754 = 54 Degrees Celsius.
According to Mastering Physics this is the incorrect answer. To me it makes sense, and after reviewing my work, I cant' seem to find the error. Any help will be greatly appreciated.