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Estimate the power radiated by the human body. Be sure to state the estimated va

ID: 2002972 • Letter: E

Question

Estimate the power radiated by the human body. Be sure to state the estimated values of all relevant quantities. You need only outline your calculations. How does this value compare with the average caloric intake for humans? (Note: Human caloric intake ~ 2,000 Calories/day ~ 8,000,000 Joules/day.)  See page 81 (78 in the 2nd Ed) of your text for the relevant equations.

You might find a surprisingly high number. It would be an appropriate answer if you were in deep space away from all other radiating bodies. A value more appropriate for on Earth can be found by accounting for radiation received by the body. The version of Eq 3.28 that accounts for this is I = (T4 - T4env), where
Tenv is the absolute temperature of the environment.
Estimate the power radiated by the human body. Be sure to state the estimated values of all relevant quantities. You need only outline your calculations. How does this value compare with the average caloric intake for humans? (Note: Human caloric intake ~ 2,000 Calories/day ~ 8,000,000 Joules/day.)  See page 81 (78 in the 2nd Ed) of your text for the relevant equations.

You might find a surprisingly high number. It would be an appropriate answer if you were in deep space away from all other radiating bodies. A value more appropriate for on Earth can be found by accounting for radiation received by the body. The version of Eq 3.28 that accounts for this is I = (T4 - T4env), where
Tenv is the absolute temperature of the environment.

Explanation / Answer

Power radiated by human body in deep space away = eAT4

                                                                                     = 0.975.67108W/m2K41.7m2(310K)4

                                                                                                       = 860 W

Here, we have considered average surface area of human =1.7 m2

Power radiated by human body on Earth = eA(T4-T4env)

                                                                                     = 0.975.67108W/m2K41.7m2((310K)4(293K)4)

                                                                                                       = 180 W

=> In Deep space away energy radiated = 74*106 J per day

enery consumed per day = 8*106 J per day

=> energy radiated by human being in deep space away is much larger than energy consumed .

Energy consumed on earth by human = 15*106 J per day

This value comes to be much closer with the energy consumed .

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