Overall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The mechanisms of elimination are radiation, evaporation of sweat (2,430 kJ/kg), evaporation from the lungs (38 kJ/h), conduction, and convection. A person working out in a gym has a metabolic rate of 2,500 kJ/h. His body temperature is 37°C, and the outside temperature 28°C. Assume the skin has an area of 2.0 m2 and emissivity of 0.97. (0 = 5.6696 x 10-8 w/m2. K4) (a) At what rate is his excess thermal energy dissipated by radiation? (Enter your answer to at least one decimal place.) (b) If he eliminates 0.41 kg of perspiration during that hour, at what rate is thermal energy dissipated by evaporation of sweat? (Enter your answer to at least one decimal place.) (c) At what rate is energy eliminated by evaporation from the lungs? (Enter your answer to at least one decimal place.) (d) At what rate must the remaining excess energy be eliminated through conduction and convection?

Overall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The mechanisms of elimination are radiation, evaporation of sweat (2,430 kJ/kg), evaporation from the lungs (38 kJ/h), conduction, and convection. A person working out in a gym has a metabolic rate of 2,500 kJ/h. His body temperature is 37°C, and the outside temperature 28°C. Assume the skin has an area of 2.0 m2 and emissivity of 0.97. (0 = 5.6696 x 10-8 w/m2. K4) (a) At what rate is his excess thermal energy dissipated by radiation? (Enter your answer to at least one decimal place.) (b) If he eliminates 0.41 kg of perspiration during that hour, at what rate is thermal energy dissipated by evaporation of sweat? (Enter your answer to at least one decimal place.) (c) At what rate is energy eliminated by evaporation from the lungs? (Enter your answer to at least one decimal place.) (d) At what rate must the remaining excess energy be eliminated through conduction and convection?

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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Question

Overall, 80% of the energy used by the body must be eliminated as excess thermal energy and needs to be dissipated. The mechanisms of elimination are radiation, evaporation of sweat (2,430 kJ/kg),
evaporation from the lungs (38 kJ/h), conduction, and convection.
A person working out in a gym has a metabolic rate of 2,500 kJ/h. His body temperature is 37°C, and the outside temperature 28°C. Assume the skin has an area of 2.0 m2 and emissivity of 0.97.
(0 = 5.6696 x 10-8 W/m2 . K4)
(a) At what rate is his excess thermal energy dissipated by radiation? (Enter your answer to at least one decimal place.)
W
(b) If he eliminates 0.41 kg of perspiration during that hour, at what rate is thermal energy dissipated by evaporation of sweat? (Enter your answer to at least one decimal place.)
w
(c) At what rate is energy eliminated by evaporation from the lungs? (Enter your answer to at least one decimal place.)
w
(d) At what rate must the remaining excess energy be eliminated through conduction and convection?
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