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. A person\'s body is producing energy internally due to metabolic processes. If

ID: 1570713 • Letter: #

Question

. A person's body is producing energy internally due to metabolic processes. If the body loses more energy than metabolic processes are generating, its temperature will drop. If the drop is severe, it can be life-threatening. Suppose a person is unclothed and energy is being lost via radiation from a body surface area of 1.51 m2, which has a temperature of 34 °C and an emissivity of 0.764. Suppose that metabolic processes are producing energy at a rate of 138 J/s. What is the temperature in kelvins of the coldest room in which this person could stand and not experience a drop in body temperature? Number Units

Explanation / Answer

we know that according to Stefan boltzmann law

amount of heat radiated per sec Q   /t =eA(T14 -T24)---1

heat radiated per sec Q   /t = 138J/s.

= stefan's constant =5.67*10-8Wm-2K-4

A = area of the body = 1.51 m2

T1 = temperature of man =34 degrees C = 34 +273 = 307K

T2 = temperature of room

e = emissivity of body = 0.764

Value put in above equation

138 = (0.764*(5.67*10-8)*1.51)((307)4-T24)

T2= [(307)4-138/(0.764*(5.67*10-8)*1.51)]0.25

T2= 286.88 K