In this problem you will consider the balance of thermal energy radiated and abs

Question

In this problem you will consider the balance of thermal energy radiated and absorbed by a person. Assume that the person is wearing only a skimpy bathing suit of negligible area. As a rough approximation, the area of a human body may be considered to be that of the sides of a cylinder of length L=2.0m and circumference C=0.8m. For the Stefan-Boltzmann constant use =5.67×108W/m2/K4. If the surface temperature of the skin is taken to be Tbody=30C, how much thermal power Prb does the body described in the introduction radiate? Take the emissivity to be e=0.6. Express the power radiated into the room by the body numerically, rounded to the nearest 10 W.

Explanation / Answer

Given that

The  cylinder of length (L) =2.0m

Circumference C=0.8m

The Stefan-Boltzmann constant use =5.67×108W/m2/K4.

The temperature of the in absolute scale is (T) =300C =30+273 =303K

We know that the expression for the power radiated is

P =*e*AT4

Where Stefan-Boltzmann constant =5.67×108W/m2/K4

e is the emissivity =0.6

A is the Area (A) =(0.8)(2.0) =1.6m2

T is the absolute temperature =303K

Now substituting all the values in P =*e*AT4 =458.8W which is nearly 460W

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