Radiant heat makes it impossible to stand close to a hot lava flow. calculate the rate of heat loss by radiation from 1.00 m^2 of 1190°c fresh lava into 30.0°c surroundings, assuming lava's emissivity is 1.

259.274 kW

Explanation:

Given:

Area of the lava, A = 1.00 m²

Temperature of the surrounding, T₁ = 30.0° C = 303 k

Temperature of the lava, T₂ = 1190° C = 1463 K

emissivity, e = 1

Now,

from the Stefan-Boltzmann law of radiation the rate of heat loss is given as,

u = σeA(T₂⁴ - T₁⁴)

where,

u = rate of heat loss

σ = Stefan-Boltzmann constant =  5.67 × 10⁻⁸ W/m²∙K⁴

on substituting the respective values, we get

u = 5.67 × 10⁻⁸ × 1 × 1 × (1463⁴ - 303⁴)

or

u = 259274.957 W

or

u = 259.274 kW

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.