Question

At high noon, the sun delivers 1150 w to each square meter of a blacktop road. if the hot asphalt loses energy only by radiation, what is its equilibrium temperature?

Answer 1

Stephen`s Law:
P = (Sigma) · A · e · T^4
P in = P out
e = 1 for blacktop;
1150 W = (Sigma) · T^4
(Sigma) = 5.669 · 10 ^(-8) W/m²K^4
T^4 = 1150 : ( 5.669 · 10^(-8) )
T^4 = 202.875 · 10^8

`T = \sqrt[4]{202.857 * 10 ^(8) }`
T = 3.774 · 10² = 377.4 K
Answer: Equilibrium temperature is 377.4 K.