Answer:
142.6 joules is the amount of heat that a person could radiate per second
Explanation:
To solve this, we have to apply Stephan-Boltzmann's law:
Q/ΔT = σ . ε . A . (Te⁴ - Ta⁴) where
σ = Boltzmann's constant → 5.67×10⁻⁸ W/m² . K⁴
ε = Body's emissivity, in this case = 1
Α = Surface, we assume a value of 2m²
Te = Temperature of the body's surface, in this case 30°C
Ta = Temperature of the room, where the body is. In this case, 18°C
Notice that T° must be Absolute T° → T°C + 273
18°C + 273 = 291K
30°C + 273 = 303K . Let's replace data:
Q/s = 5.67×10⁻⁸ W/m² . K⁴ . 1 . 2m² (303⁴K - 291⁴K)
Q/s = 5.67×10⁻⁸ W/m² . K⁴ . 1 . 2m² . 1.26×10⁻⁹K⁴
Q/s = 142.6 W
1 W = Joules/s
