Chapter 16: Heat Transfer

Question 1

Metals are both good heat conductors and good electrical conductors because of the?

Answer 1

looseness of outer electrons in metal atoms.

Question 2

Your feet feel warmer on a rug than on a tile floor because a rug?

Answer 2

is a better insulator than tile.

Question 3

Warm air rises because faster-moving molecules tend to move to regions of less?

Answer 3

density and less pressure.

Question 4

The higher the temperature of an object the _______ the wavelengths it ________?

Answer 4

the shorter the wavelengths it radiates.

Question 5

An object will normally be a net radiator of energy when its temperature is?

Answer 5

higher than its surroundings.

Question 6

Which body glows with electromagnetic waves: only the Sun; only the Earth; both the Sun and the Earth or neither the Sun or the Earth?

Answer 6

both the Sun and the Earth.

Question 7

The technology for orbiting solar power plants: awaits the next century; already exists or is theoretically impossible?

Answer 7

already exists.

Question 8

The planet Earth loses heat mainly by?

Answer 8

radiation.

Question 9

Both black and white road surfaces absorb sunlight. At the end of a sunny day the warmer road surface will be?

Answer 9

the black surface.

Question 10

Energy transfer by convection is primarily restricted to?

Answer 10

fluids.

Question 11

Conduction

Answer 11

The transfer of heat energy by molecular and electron collisions within a substance (especially a solid).

Question 12

Convection

Answer 12

The transfer of heat energy in a gas or liquid by means of currents in the heated fluid. The fluid moves, carrying energy with it.

Question 13

Radiation

Answer 13

The transfer of energy by means of electromagnetic waves.

Question 14

Terrestrial radiation

Answer 14

The radiation emitted by Earth to outer space.

Question 15

Newton’s law of cooling

Answer 15

The rate of loss of heat from a warm object is proportional to the temperature difference between the object and its surroundings. (Similarly for the gain of heat by a cool object.)

Question 16

Greenhouse effect

Answer 16

Warming of the lower atmosphere by short-wavelength radiation from the Sun that penetrates the atmosphere is absorbed by Earth and is reradiated at longer wavelengths that cannot easily escape Earth’s atmosphere.

Question 17

Solar constant

Answer 17

1400 J/m^2 received from the Sun each second at the top of Earth’s atmosphere on an area perpendicular to the Sun’s rays; expressed in terms of power, 1.4k W/m^2.

Question 18

Solar power

Answer 18

Energy per unit time derived from the Sun.

Question 19

The surface of Earth loses energy to outer space due mostly to: a) conduction; b) convection; c) radiation; d) radioactivity;

Answer 19

c) radiation;

Radiation is the only choice, given the vacuum of outer space.

Question 20

Low-frequency vibration produces?

Answer 20

Long-wavelength waves

Question 21

High-frequency vibration produces?

Answer 21

Short-wavelength waves

Question 22

From the Sun’s surface comes light, also known as?

Answer 22

Electromagnetic radiation or solar radiation

Question 23

From the Earth’s surface comes _________ radiation in the form of _______ waves.

Answer 23

From the Earth’s surface comes terrestrial radiation in the form of infrared waves (below our threshold of sight).

Question 24

Which body glows with electromagnetic waves: a) Sun; b) Earth; c) both a and b; d) none of the above

Answer 24

c) both a and b;

Earth glows in long-wavelength radiation, while the Sun glows in shorter waves.

Question 25

Any material that absorbs more than it emits is a?

Answer 25

Net absorber

Question 26

Any material that emits more than it absorbs is a?

Answer 26

Net emitter

Question 27

A hot pizza placed in the snow is a net: a) absorber; b) emitter; c) both a and b; d) none of the above;

Answer 27

b) emitter;

Net energy flow goes from higher to lower temperature.

Question 28

Which melts faster in sunshine, dirty snow or clean snow: a) dirty snow; b) clean snow; c) both a and b; d) none of the above;

Answer 28

a) dirty snow;

Dirty snow absorbs more sunlight, whereas clean snow reflects more.