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posted by cz on .
A black thinwalled cylindrical can, 10.0 cm in diameter and 20.0 cm tall is filled with water at 100°C and suspended in a 20°C room. Determine the initial rate of heat transfer due to radiation, and the initial rate of change of temperature of the water. (Neglect any calorimetric effects of the can)

Note that they only ask for the heat transfer due to radiation. Use the StefanBoltzmann law.
The can's temperatuire will be 373 K, initially.
The room temperature is 293 K.
Q = M*C*dT/dt
You want the cooldown rate dT/dt
Q = A*sigma*(373^4  293^4)
C = 4184 J/kg*K is the specific heat of water
A is the can's outside arwea in m^2
sigma is the StefanBoltzmann constant. Assume can and room wall emissivity = 1.
M is the water mass 
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