find the net rate of radiation by a pot at 35.7C that has been placed in a -19.7

Question

find the net rate of radiation by a pot at 35.7C that has been placed in a -19.7C freezer. The pots surface area is 0.149m^2 and its emissivity is 0.523. You have a 80.5 cm long copper rod with a rectangular cross section of dimensions 5.95 cm by 7.89 cm. you maintain the ends of the rod at 57.5C and 86.1C but otherwise insulate the rod from its environment. Find the heat current through the rod. The thermal conductivity of copper is 385 W/(m*k) find the net rate of radiation by a pot at 35.7C that has been placed in a -19.7C freezer. The pots surface area is 0.149m^2 and its emissivity is 0.523. You have a 80.5 cm long copper rod with a rectangular cross section of dimensions 5.95 cm by 7.89 cm. you maintain the ends of the rod at 57.5C and 86.1C but otherwise insulate the rod from its environment. Find the heat current through the rod. The thermal conductivity of copper is 385 W/(m*k) find the net rate of radiation by a pot at 35.7C that has been placed in a -19.7C freezer. The pots surface area is 0.149m^2 and its emissivity is 0.523. You have a 80.5 cm long copper rod with a rectangular cross section of dimensions 5.95 cm by 7.89 cm. you maintain the ends of the rod at 57.5C and 86.1C but otherwise insulate the rod from its environment. Find the heat current through the rod. The thermal conductivity of copper is 385 W/(m*k)

Explanation / Answer

We assume that heat is lost only via radiation. Apply the Stefan-Boltzman Law:

P/A = e*s*T^4 where e = emissivity of pot, A =surface area, s = Stefan-Boltzman constant and T = temperature, P = radiated power

Now radiation from the pot into the environment (freezer) and radiation from the freezer to the pot. The ne radiation from the pot to the freezer is:

(P/A)net = e*s*(Tp^4 - Tf^4) where Tp = pot temperature and Tf = freezer temperature

Tp = 273 K + 35.7 = 308.7 K

Tf = 273 - 19.7 = 253.3 K

s = 5.67x10^-8 W/m^2/K^4

(P/A)net = 147.222 W/m^2

---> Pnet = (P/A)net* A = 0.6911 W

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