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Review Assessment: Quiz 10 (F04)
Name: Quiz 10 (F04)
Status: Needs Grading
Score: Grade not available  
Instructions:

  Question 1   Multiple Choice 0 of 0.62 point(s)  
Incorrect Question 1 text
Question 1 answers
Your Answer: Incorrect evidence that M87 may have grown to be a giant elliptical through collisions with other, smaller galaxies, some of whose material may have fallen into M87's center
Correct Answer: Correct the discovery of a gravitational lens in M87
Feedback: Incorrect.

  Question 2   Multiple Choice 0.63 of 0.63 point(s)  
Correct Question 2 text
Question 2 answers
Your Answer: Correct the extremely bright center of a distant galaxy, thought to be powered by a massive black hole
Correct Answer: Correct the extremely bright center of a distant galaxy, thought to be powered by a massive black hole

  Question 3   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect the light from the galaxy as it is today, but it is blueshifted
Correct Answer: Correct the light from the galaxy as it was 100 million years ago and it is redshifted

  Question 4   Multiple Choice 0 of 0.63 point(s)  
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Your Answer: Incorrect varies depending on how far away the object is
Correct Answer: Correct about 10 light-hours across

  Question 5   Multiple Choice 0.63 of 0.63 point(s)  
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Your Answer: Correct massive objects bend light beams that are passing nearby.
Correct Answer: Correct massive objects bend light beams that are passing nearby.

  Question 6   Multiple Choice 0.63 of 0.63 point(s)  
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Your Answer: Correct Infrared observations show that many stars are forming near the centers of active galaxies.
Correct Answer: Correct Infrared observations show that many stars are forming near the centers of active galaxies.

  Question 7   Multiple Choice 0.63 of 0.63 point(s)  
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Question 7 answers
Your Answer: Correct They are not as bright as a normal star and are not visible across great distances of space.
Correct Answer: Correct They are not as bright as a normal star and are not visible across great distances of space.

  Question 8   Multiple Choice 0.63 of 0.63 point(s)  
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Question 8 answers
Your Answer: Correct by gravity, which converts potential energy of matter falling toward a central black hole into kinetic energy, which is then converted to thermal energy by collisions among the particles of matter
Correct Answer: Correct by gravity, which converts potential energy of matter falling toward a central black hole into kinetic energy, which is then converted to thermal energy by collisions among the particles of matter

  Question 9   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect 8 to 12 billion years old
Correct Answer: Correct 12 to 20 billion years old

  Question 10   Multiple Choice 0.62 of 0.62 point(s)  
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Question 10 answers
Your Answer: Correct ultraviolet
Correct Answer: Correct ultraviolet
Feedback: Correct.

  Question 11   Multiple Choice 0 of 0.63 point(s)  
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Your Answer: Incorrect 100 km.
Correct Answer: Correct 2.5 m.

  Question 12   Multiple Choice 0.62 of 0.62 point(s)  
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Question 12 answers
Your Answer: Correct From the period-luminosity relation for Cepheids, he was able to determine the distance to Andromeda and show that it was far outside the Milky Way Galaxy.
Correct Answer: Correct From the period-luminosity relation for Cepheids, he was able to determine the distance to Andromeda and show that it was far outside the Milky Way Galaxy.

  Question 13   Multiple Choice 0.62 of 0.62 point(s)  
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Your Answer: Correct Beyond the cosmological horizon, we are looking back to a time before the universe had formed.
Correct Answer: Correct Beyond the cosmological horizon, we are looking back to a time before the universe had formed.

  Question 14   Essay Needs Grading  
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Your Answer: You would get 10 solar luminosities per solar mass.
Correct Answer: Correct If a galaxy has a lower mass-to-light ratio than 1, then the ratio of massive hot stars to dim cool stars in this galaxy must be higher than that ratio in our own galaxy (or indeed every other galaxy observed to date). If I had confidence in my observations, I might suspect that the star formation in this galaxy must have produced an unusual predominance of high-mass stars.
  Feedback:

  Question 15   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect They are very bright, so they can be used to determine the distances to galaxies billions of light-years away.
Correct Answer: Correct both A and B

  Question 16   Multiple Choice 0.62 of 0.62 point(s)  
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Question 16 answers
Your Answer: Correct parallax, main-sequence fitting, Cepheid variables, Tully-Fisher relation, Hubble's law
Correct Answer: Correct parallax, main-sequence fitting, Cepheid variables, Tully-Fisher relation, Hubble's law

  Question 17   Multiple Choice 0 of 0.63 point(s)  
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Your Answer: Incorrect 50 percent
Correct Answer: Correct 95 percent

  Question 18   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect 1 trillion.
Correct Answer: Correct 100 billion.

  Question 19   Multiple Choice 0.62 of 0.62 point(s)  
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Question 19 answers
Your Answer: Correct White-dwarf supernovae occur only among young and extremely bright stars.
Correct Answer: Correct White-dwarf supernovae occur only among young and extremely bright stars.

  Question 20   Multiple Choice 0.63 of 0.63 point(s)  
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Your Answer: Correct We observe clouds of atomic hydrogen far from the galactic center orbiting the galaxy at unexpectedly high speeds, higher speeds than they would have if they felt only the gravitational attraction from objects that we can see.
Correct Answer: Correct We observe clouds of atomic hydrogen far from the galactic center orbiting the galaxy at unexpectedly high speeds, higher speeds than they would have if they felt only the gravitational attraction from objects that we can see.

  Question 21   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect Dr. Smith believes that the Andromeda Galaxy (a member of our Local Group) is moving away from us at a faster speed than Dr. Jones believes.
Correct Answer: Correct Dr. Smith believes that the universe is younger than Dr. Jones believes.

  Question 22   Multiple Choice 0.62 of 0.62 point(s)  
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Question 22 answers
Your Answer: Correct An elliptical galaxy lacks a disk component.
Correct Answer: Correct An elliptical galaxy lacks a disk component.

  Question 23   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect a few light months is about the size of a typical galaxy, and astronomers think quasars are active galaxies
Correct Answer: Correct quasars show variations in their energy output that have a period of a few months
Feedback: Incorrect.

  Question 24   Multiple Choice 0.63 of 0.63 point(s)  
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Question 24 answers
Your Answer: Correct Galaxies were closer together in the past because the universe was smaller.
Correct Answer: Correct Galaxies were closer together in the past because the universe was smaller.

  Question 25   Multiple Choice 0 of 0.63 point(s)  
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Your Answer: Incorrect The Milky Way was blocking our view of distant galaxy clusters.
Correct Answer: Correct The medium emits X rays, which are blocked by the earth's atmosphere and require X-ray satellites in space in order to be observed.

  Question 26   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect it isn't light that escapes from the black holes in quasars, but x-rays and gamma-rays, which work by completely different rules
Correct Answer: Correct the energy we see from quasars comes from regions where matter is falling in still outside the event horizon
Feedback: Incorrect.

  Question 27   Multiple Choice 0 of 0.63 point(s)  
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Question 27 answers
Your Answer: Incorrect There are not enough neutrinos to make up all the dark matter.
Correct Answer: Correct Neutrinos travel at extremely high speeds and can escape a galaxy's gravitational pull.

  Question 28   Multiple Choice 0 of 0.62 point(s)  
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Your Answer: Incorrect the entire universe was hotter 8 billion years ago, so everything was bluer in color
Correct Answer: Correct as galaxies get older, the stars within them age, and the galaxies get less blue with time
Feedback: Incorrect.

  Question 29   Multiple Choice 0 of 0.63 point(s)  
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Question 29 answers
Your Answer: Incorrect There is far more dark matter than visible matter in the universe.
Correct Answer: Correct White-dwarf supernovae are slightly dimmer than expected for a coasting universe.

  Question 30   Multiple Choice 0.62 of 0.62 point(s)  
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Question 30 answers
Your Answer: Correct the more distant a galaxy is from us, the faster it moves away from us
Correct Answer: Correct the more distant a galaxy is from us, the faster it moves away from us

  Question 31   Multiple Choice 0.63 of 0.63 point(s)  
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Question 31 answers
Your Answer: Correct determining their redshifts.
Correct Answer: Correct determining their redshifts.

  Question 32   Multiple Choice 0 of 0.63 point(s)  
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Your Answer: Incorrect Hubble's law of expansion applies only to the space between galaxies.
Correct Answer: Correct Their gravity is strong enough to hold them together