A ceramic teapot (epsilon(e) = 0.70) and a shiny one (epsilon(e) = 0.10) each hold 0.50 L of tea at 99 degrees C.
a) Estimate the rate of heat loss from each. Consider only radiation, and assume the surroundings are at 20 degrees C.
b.)Estimate the temperature drop after 30 min for each.
change in Q/change in T = epsilon*Stefan constant*Area (T^4 - T^4)
The Attempt at a Solution
My professor told us to assume that the tea pot is a sphere so we can solve for the area.
so V = 4/3pi R^3 = .05 m^3 R=.2285
A = 4pi R^2 = .6563
Ceramic = (.70)(5.67*10^-8)(.6563)((372^4)-(293^4))
Ceramic = 306.87 W
Shiny = (.1)*5.67*10^-8)(.6563)((372^4)-(293^4))
Shiny = 43.84
Then we're supposed to use two sig figs, which I did,and the program I used keeps telling me I am wrong.