A1.88-m (6 ft 2 in.) man has a mass of 81 kg, a body surface area of 1.8 m2, and a skin temperature of 35.2 ∘c. normally, 80% of the food calories he consumes go to heat; the rest goes to mechanical energy. his emissivity e is 1 because his body radiates almost entirely nonvisible infrared energy, which is not affected by skin pigment. (careful! his body at 35.2 ∘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?