A black thin-walled 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)

1 answer

Note that they only ask for the heat transfer due to radiation. Use the Stefan-Boltzmann 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 Stefan-Boltzmann constant. Assume can and room wall emissivity = 1.

M is the water mass