Final answer:
To find the net rate of heat transfer by radiation, use the formula Q = e*A*(T₂^4 - T₁^4), where e is the emissivity, A is the surface area, T₂ is the temperature of the object, and T₁ is the temperature of the surroundings.
Step-by-step explanation:
To find the net rate of heat transfer by radiation, we can use the formula Q = e*A*(T₂^4 - T₁^4). Here, e is the emissivity, A is the surface area, T₂ is the temperature of the object, and T₁ is the temperature of the surroundings.
Let's calculate the net rate of heat transfer for the given situation:
Q = 0.521 * 0.123 * (49.7 + 273)^4 - (-21.5 + 273)^4)
By plugging in the values, we can calculate the net rate of heat transfer by radiation.