A 1.88-m (6 ft 2 in.)1.88-m (6 ft 2 in.) man has a mass of 86 kg, a body surface area of 1.9 m2, and a skin temperature of 34.5 ∘C. Normally, 80% of the food calories he consumes go to heat; the rest goes to mechanical energy. His emissivity e is 11 because his body radiates almost entirely nonvisible infrared energy, which is not affected by skin pigment. (Careful! His body at 34.5 ∘C radiates into the environment at 20.0 ∘C, but the environment also radiates back into his body. The net rate of radiation is Pnet=Pbody−Penvironment.) To keep his body’s temperature constant, how many food calories should he eat per day if he is in a room at 20.0 ∘C and he loses heat only through radiation? Does the answer seem reasonable? Y/N?
A 1.88-m (6 ft 2 in.)1.88-m (6 ft 2 in.) man has a mass of 86 kg, a body surface area of 1.9 m2, and a skin temperature of 34.5 ∘C. Normally, 80% of the food calories he consumes go to heat; the rest goes to mechanical energy. His emissivity e is 11 because his body radiates almost entirely nonvisible infrared energy, which is not affected by skin pigment. (Careful! His body at 34.5 ∘C radiates into the environment at 20.0 ∘C, but the environment also radiates back into his body. The net rate of radiation is Pnet=Pbody−Penvironment.)
To keep his body’s temperature constant, how many food calories should he eat per day if he is in a room at 20.0 ∘C and he loses heat only through radiation?
Does the answer seem reasonable? Y/N?
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