4.2. An average person generates heat at a rate of 84W while resting in a room at T-. Assuming one- quarter of this heat is lost from the head and taking the emissivity of the skin to be 0.9, determine the average surface temperature of the head when it is not covered. The head can be approximated as a 30 cm-diameter sphere, and the interior surfaces of the room can be assumed to be at the room temperature. The surface temperature can be guessed at 40°C for the evaluation of the properties and h. g=9.81 m/s?, o=5.67x10³ W/m²K* Group 4,5,6: T-= 26°C Нead Air T. = 25°C D= 30 cm 60=3 Good luck...

4.2. An average person generates heat at a rate of 84W while resting in a room at T-. Assuming one- quarter of this heat is lost from the head and taking the emissivity of the skin to be 0.9, determine the average surface temperature of the head when it is not covered. The head can be approximated as a 30 cm-diameter sphere, and the interior surfaces of the room can be assumed to be at the room temperature. The surface temperature can be guessed at 40°C for the evaluation of the properties and h. g=9.81 m/s?, o=5.67x10³ W/m²K* Group 4,5,6: T-= 26°C Нead Air T. = 25°C D= 30 cm 60=3 Good luck...

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Concept explainers

Conduction and Convection

When energy travels from one object to another it is said to have undergone heat transfer. Heat transfer is nothing but the transfer of thermal energy or internal energy from one thing to another, like e.g., when a vessel with water, kept on top of a burner, heats up because of the flame underneath it.

Question

4.2. An average person generates heat at a rate of 84W while resting in a room at T.. Assuming one-
quarter of this heat is lost from the head and taking the emissivity of the skin to be 0.9, determine the
average surface temperature of the head when it is not covered. The head can be approximated as a
30 cm-diameter sphere, and the interior surfaces of the room can be assumed to be at the room
temperature. The surface temperature can be guessed at 40°C for the evaluation of the properties and
h.
g=9.81 m/s?, o=5.67x108 W/m?K4
Group 4,5,6: T-= 26°C
Нead
Air
T, = 25°C
D= 30 cm
60= 3
Good luck...

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