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AP World History Unit 7 - Lesson 7.5

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Social Psychology: Conformity and Obedience

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Middle Childhood: Physical Growth

CH 19 HW

If a newly forming star has an excess of heat, then it will likely have

slower contraction rate.

rapid contraction rate.

more gravity.

less gravity.

The gravitational contraction of an interstellar cloud is primarily the result of its

pressure.

diameter.

composition.

mass.

As a clump of interstellar gas contracts to become a main-sequence star, its changing position on the H-R diagram tells us __________.

how its outward appearance is changing

how it moves through the galaxy

the time during which it existed in the history of the universe

When does a newly forming star have the greatest luminosity?

when its internal temperature becomes high enough for nuclear fusion

when its surface temperature is the highest

when it first becomes a main-sequence star

when it is a shrinking protostar with no internal fusion

When a newly forming star is at its greatest luminosity, what is its energy source?

gravitational contraction

radioactive decay of unstable isotopes

nuclear fusion of hydrogen into helium

A newly forming star has no energy source because it does not shine at all until it becomes a true main-sequence star.

The "dust" component of the interstellar medium is mostly particles of about what size?

pebbles

smoke particles

boulders

grains of sand

The red/pink color associated with star-forming regions is due to what kind of process?

scattering

emission

reflection

absorption

What kind of light would be the best to use to look inside a cold dark cloud and see the warm stars forming inside?

x-ray

ultraviolet

infrared

visible

The interstellar cloud from which our Sun formed was

slightly larger than the Sun.

comparable in size to Saturn's orbit.

comparable in mass to the solar system.

thousands of times more massive than the Sun.

A protostar that will eventually turn into a star like the Sun is significantly

more luminous.

less massive than the Sun.

smaller.

fainter.

How do the properties of long-lived stars compare to those of short-lived stars?

Long-lived stars begin their lives with more mass and a larger amount of hydrogen fuel.

Long-lived stars begin their lives with less mass and a smaller amount of hydrogen fuel.

Long-lived stars are more luminous during their main-sequence lives.

Long-lived stars are less luminous during their main-sequence lives.

A main-sequence star twice as massive as the Sun would last __________.

about half as long as the Sun

much less than half as long as the Sun

about twice as long as the Sun

much longer than twice as long as the Sun

The current theory of star formation is based upon

carefully studying the births of a few stars.

systematically measuring the masses and rotation rates of interstellar clouds.

observations made primarily at short wavelengths.

amassing evidence from many different regions of the Galaxy.

If the initial interstellar cloud in Figure19.14 in the textbook ("Generations of Star Formation") were much more massive, the result would be

stronger shock waves.

the formation of more stars.

stars forming closer together.

contraction of the cloud due to stronger gravitational attraction.

A typical open cluster will dissolve in about the same amount of time as the time since

dinosaurs walked on Earth.

Earth was formed.

North America was first visited by Europeans.

the universe formed.

One of the primary differences between the Pleiades cluster, shown in Figure19.17(a) in the textbook, and Omega Centauri, shown in Figure19.18(a), is that the Pleiades cluster is much

farther away.

denser.

larger.

younger.

If the HR diagram shown in Figure19.18(b) in the textbook ("Globular Cluster") were redrawn to illustrate a much younger cluster, the main-sequence turnoff would shift to

spectral classification of K or M.

higher frequency.

higher temperature.

higher pressure.

In the formation of a star cluster with a wide range of stellar masses, is it possible for some stars to die out before others have finished forming?

Low-mass stars evolve at a slower rate than high-mass ones; this principle applies equally to the process of formation. If a star cluster forms any O or B stars, they will use up their hydrogen and die out before many of the lowest mass stars have time to evolve onto the main sequence.

Low-mass stars evolve at a slower rate than high-mass ones; but this principle does not apply equally to the process of formation. If a star cluster forms any O or B stars, they will use up their hydrogen and die out before many of the lowest mass stars have time to evolve onto the main sequence.

Low-mass stars evolve at a slower rate than high-mass ones; but this principle does not apply equally to the process of formation. If a star cluster forms any O or B stars, they wont be able to evolve onto the main sequence before many of the lowest mass stars use up their hygrogen and die out.

Low-mass stars evolve more rapidly than high-mass ones; this principle applies equally to the process of formation. If a star cluster forms any O or B stars, they wont be able to evolve onto the main sequence before many of the lowest mass stars use up their hygrogen and die out.