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2. Question 1 Pulsars usually show all of the following EXCEPT
extremely rapid rotation.
high-temperature fusion reactions.
a narrow regular pulse of radiation.
high-speed motion through the Galaxy.
an intense magnetic field.
Answer: b
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3. Question 1 Pulsars usually show all of the following EXCEPT
extremely rapid rotation.
high-temperature fusion reactions.
a narrow regular pulse of radiation.
high-speed motion through the Galaxy.
an intense magnetic field.
Explanation: Pulsars are neutron stars no longer undergoing fusion in their cores.
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4. Question 2 Many millisecond pulsars lie within emission nebulae.
giant molecular clouds.
globular clusters.
planetary nebulae.
open clusters.
Answer: c
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5. Question 2 Many millisecond pulsars lie within emission nebulae.
giant molecular clouds.
globular clusters.
planetary nebulae.
open clusters.
Explanation: The cores of globular clusters are densely packed with stars, suggesting that millisecond pulsars might result from “spinning up” as a result of stellar encounters.
The core of globular cluster 47 Tucanae
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6. Question 3 The lighthouse model explains how
pulsars can be used as interstellar navigation beacons.
the period of pulsation increases as a neutron star collapses.
pulsars have their rotation axis pointing toward Earth.
a rotating neutron star generates an observable beam of light.
Answer: d
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7. Question 3 The lighthouse model explains how
pulsars can be used as interstellar navigation beacons.
the period of pulsation increases as a neutron star collapses.
pulsars have their rotation axis pointing toward Earth.
a rotating neutron star generates an observable beam of light.
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8. Question 4 One possible explanation for a gamma-ray burster is
matter spiraling into a large black hole.
the collision of neutron stars in a binary system.
variations in the magnetic fields of a pulsar.
repeated nova explosions.
All of the above are possible.
Answer: b
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9. Question 4 One possible explanation for a gamma-ray burster is
matter spiraling into a large black hole.
the collision of neutron stars in a binary system.
variations in the magnetic fields of a pulsar.
repeated nova explosions.
All of the above are possible.
Explanation: Gamma-ray bursts vary in length, and the coalescence of two neutron stars seems to account for short bursts.
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10. Question 5 Cygnus X-1 is NASA’s latest X-ray orbiting telescope.
a millisecond pulsar with three planets.
the strongest X-ray eclipsing binary system.
a likely black hole binary star system.
the first gamma-ray burster spotted in X-rays.
Answer: d
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11. Question 5 Cygnus X-1 is NASA’s latest X-ray orbiting telescope.
a millisecond pulsar with three planets.
the strongest X-ray eclipsing binary system.
a likely black hole binary star system.
the first gamma-ray burster spotted in X-rays.
Explanation: Cygnus X-1 is an X-ray source with one visible star orbited by an unseen companion of at least 10 solar masses and very rapid changes in the signal indicating a small source.
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12. Question 6 The force of gravity can pull on a beam of light.
a massive object.
neutrinos.
antimatter.
All of the above are correct.
Answer: e
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13. Question 6 The force of gravity can pull on a beam of light.
a massive object.
neutrinos.
antimatter.
All of the above are correct.
Explanation: Gravity is described by general relativity as a bending of space, and all particles, including photons, move through warped space along curved paths.
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14. Question 7 If the sun was replaced by a 1-solar-mass black hole,
Earth’s orbit would not change.
Earth would be pulled into the black hole.
X-rays would destroy Earth.
Earth would be torn apart from the tidal force.
life would be unchanged.
Answer: a
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15. Question 7 If the sun was replaced by a 1-solar-mass black hole,
Earth’s orbit would not change.
Earth would be pulled into the black hole.
X-rays would destroy Earth.
Earth would be torn apart from the tidal force.
life would be unchanged.
Explanation: The force of gravity depends only on mass and distance, not the type of matter or its size.
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16. Question 8 The event horizon of a black hole
is the point where X-rays emerge.
is the physical surface of the hole.
defines the outer edge of an accretion disk.
is measured by the Schwarzschild radius.
extends for millions of miles into space.
Answer: d
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17. Question 8 The event horizon of a black hole
is the point where X-rays emerge.
is the physical surface of the hole.
defines the outer edge of an accretion disk.
is measured by the Schwarzschild radius.
extends for millions of miles into space.
Explanation: The event horizon is the surface of an imaginary sphere around a collapsed object inside of which nothing, including light, can escape.
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18. Question 9
The equivalence between an accelerating windowless elevator in space and a stationary elevator in a gravity field
is a prediction of Newton’s theory of gravity.
explains why elevators don’t work in space.
explains why E = mc2 is true.
helps explain Einstein’s theory of gravity.
All of the above are correct.
Answer: d
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19. Question 9
The equivalence between an accelerating windowless elevator in space and a stationary elevator in a gravity field
is a prediction of Newton’s theory of gravity.
explains why elevators don’t work in space.
explains why E = mc2 is true.
helps explain Einstein’s theory of gravity.
All of the above are correct.
Explanation: Einstein reasoned in his 1915 general theory of relativity that no measurements could distinguish between the two elevators. That led to his description of gravity as a bending of space and time.
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