Chapter 14: Heat and Heat Transfer Methods

Expert-verified

Pages: 473 - 508

Book edition 1st Edition

Author(s) Paul Peter Urone

Pages 1272 pages

ISBN 9781938168000

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38 Questions for Chapter 14: Heat and Heat Transfer Methods

Suppose you walk into a sauna that has an ambient temperature of 50.0ºC . (a) Calculate the rate of heat transfer to you by radiation given your skin temperature is 37.0ºC , the emissivity of skin is 0.98, and the surface area of your body is\({\bf{1}}{\bf{.50}}\;{{\bf{m}}^{\bf{2}}}\). (b) If all other forms of heat transfer are balanced (the net heat transfer is zero), at what rate will your body temperature increase if your mass is 75.0 kg?

Found on Page 506
Thermography is a technique for measuring radiant heat and detecting variations in surface temperatures that may be medically, environmentally, or militarily meaningful.(a) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0ºC compared with that at 33.0ºC , such as on a person’s skin? (b) What is the percent increase in the rate of heat transfer by radiation from a given area at a temperature of 34.0ºC compared with that at 20.0ºC , such as for warm and cool automobile hoods?

Found on Page 506
The Sun radiates like a perfect black body with an emissivity of exactly 1. (a) Calculate the surface temperature of the Sun, given that it is a sphere with a\({\bf{7}}{\bf{.00 \times 1}}{{\bf{0}}^{\bf{8}}}\;{\bf{m}}\)radius that radiates\({\bf{3}}{\bf{.80 \times 1}}{{\bf{0}}^{{\bf{26}}}}{\bf{ W}}\)into 3-K space. (b) How much power does the Sun radiate per square meter of its surface? (c) How much power in watts per square meter is that value at the distance of Earth,\({\bf{1}}{\bf{.50 \times 1}}{{\bf{0}}^{{\bf{11}}}}{\bf{ m}}\)away? (This number is called the solar constant.)

Found on Page 506
A large body of lava from a volcano has stopped flowing and is slowly cooling. The interior of the lava is at 1200ºC , its surface is at 450ºC , and the surroundings are at 27.0ºC . (a) Calculate the rate at which energy is transferred by radiation from\({\bf{1}}{\bf{.00 }}{{\bf{m}}^{\bf{2}}}\)of surface lava into the surroundings, assuming the emissivity is 1.00. (b) Suppose heat conduction to the surface occurs at the same rate. What is the thickness of the lava between the 450ºC surface and the 1200ºC interior, assuming that the lava’s conductivity is the same as that of brick?

Found on Page 506
What effect does condensation on a glass of ice water have on the rate at which the ice melts? Will the condensation speed up the melting process or slow it down?

Found on Page 500
In very humid climates where there are numerous bodies of water, such as in Florida, it is unusual for temperatures to rise above about 35o.C (95o)F In deserts, however, temperatures can rise far above this. Explain how the evaporation of water helps limit high temperatures in humid climates.

Found on Page 501
In winters, it is often warmer in San Francisco than in nearby Sacramento, \({\rm{150 km}}\) inland. In summers, it is nearly always hotter in Sacramento. Explain how the bodies of water surrounding San Francisco moderate its extreme temperatures.

Found on Page 501
Putting a lid on a boiling pot greatly reduces the heat transfer necessary to keep it boiling. Explain why.

Found on Page 501
Freeze-dried foods have been dehydrated in a vacuum. During the process, the food freezes and must be heated to facilitate dehydration. Explain both how the vacuum speeds up dehydration and why the food freezes as a result.

Found on Page 501
When still air cools by radiating at night, it is unusual for temperatures to fall below the dew point. Explain why.

Found on Page 501

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Chapter 14: Heat and Heat Transfer Methods

College Physics (Urone)

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38 Questions for Chapter 14: Heat and Heat Transfer Methods

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