Chapter 16: Heat Transfer Flashcards
Metals are both good heat conductors and good electrical conductors because of the?
looseness of outer electrons in metal atoms.
Your feet feel warmer on a rug than on a tile floor because a rug?
is a better insulator than tile.
Warm air rises because faster-moving molecules tend to move to regions of less?
density and less pressure.
The higher the temperature of an object the _______ the wavelengths it ________?
the shorter the wavelengths it radiates.
An object will normally be a net radiator of energy when its temperature is?
higher than its surroundings.
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?
both the Sun and the Earth.
The technology for orbiting solar power plants: awaits the next century; already exists or is theoretically impossible?
already exists.
The planet Earth loses heat mainly by?
radiation.
Both black and white road surfaces absorb sunlight. At the end of a sunny day the warmer road surface will be?
the black surface.
Energy transfer by convection is primarily restricted to?
fluids.
Conduction
The transfer of heat energy by molecular and electron collisions within a substance (especially a solid).
Convection
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.
Radiation
The transfer of energy by means of electromagnetic waves.
Terrestrial radiation
The radiation emitted by Earth to outer space.
Newton’s law of cooling
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.)
Greenhouse effect
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.
Solar constant
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.
Solar power
Energy per unit time derived from the Sun.
The surface of Earth loses energy to outer space due mostly to: a) conduction; b) convection; c) radiation; d) radioactivity;
c) radiation;
Radiation is the only choice, given the vacuum of outer space.
Low-frequency vibration produces?
Long-wavelength waves
High-frequency vibration produces?
Short-wavelength waves
From the Sun’s surface comes light, also known as?
Electromagnetic radiation or solar radiation
From the Earth’s surface comes _________ radiation in the form of _______ waves.
From the Earth’s surface comes terrestrial radiation in the form of infrared waves (below our threshold of sight).
Which body glows with electromagnetic waves: a) Sun; b) Earth; c) both a and b; d) none of the above
c) both a and b;
Earth glows in long-wavelength radiation, while the Sun glows in shorter waves.
Any material that absorbs more than it emits is a?
Net absorber
Any material that emits more than it absorbs is a?
Net emitter
A hot pizza placed in the snow is a net: a) absorber; b) emitter; c) both a and b; d) none of the above;
b) emitter;
Net energy flow goes from higher to lower temperature.
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;
a) dirty snow;
Dirty snow absorbs more sunlight, whereas clean snow reflects more.
