Answer:
2.87 hours
Step-by-step explanation:
The formula of heat transfer by radiation is:
Q = A*e*σ*(T2^4 - T1^4)
where Q is the heat flux, A is the surface area, e is the emissivity, σ = 5.67*10^(-8) W/(m^2*K^4) and T are temperatures. Replacing with data (dimension are omitted):
Q = 1.3*0.75*5.67*10^(-8)*[(273.15 + 36)^4 - (273.15 +17)^4]
Q = 113.156 W or 113.156 J/s
If 1 Calorie is equivalent to 4186 J, then 280 Calories are equivalent to 280*4186 = 1172080 J
If 113.156 J are emitted in 1 second, then 1172080 are emitted in 1172080/113.156 = 10358.0897 seconds or approximately 2.87 hours