A human body produces about 100 W of heat to keep themselves warm. Suppose a per

Question

A human body produces about 100 W of heat to keep themselves warm. Suppose a person (surface area about 1.7 m2) is outside where the temperature is -5oC. Assume that wearing clothes makes the person's clothing surface temperature lower than body temperature. What should the surface temperature of their outerwear be, so that they can maintain their body temperature? Estimate the emissivity as about 1, and the convective heat transfer coefficient as 10 W/(m2K). If you make approximations neglecting small term(s), justify your approximation.

Explanation / Answer

heat produced = convective heat transfer coefficient * surface area * (temperature difference)

100 = (10) (1.7) (T-(-5))

100 = (10) (1.7) (T + 5)

T = 0.88 degrees celcius

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