Question 1

How long does a short gamma ray burst (short GRB) typically last?

Accepted Answer

A) about 2 ms 
B) about 2 s 
C) about 2 min 
D) about 2 hours 
A) about 2 ms 
B) about 2 s 
C) about 2 min 
D) about 2 hours

Question 2

What would happen to the gravitational force on Earth if the Sun were to be replaced by a 1-Mε black hole?

Accepted Answer

A) It would become extremely high, sufficient to pull Earth into it. 
B) It would double in strength. 
C) It would be much less, because the gravitational field of a black hole exists only very close to it. 
D) It would remain as it is now. 
A) It would become extremely high, sufficient to pull Earth into it. 
B) It would double in strength. 
C) It would be much less, because the gravitational field of a black hole exists only very close to it. 
D) It would remain as it is now.

Question 3

If you look for electrons emitted from the vicinity of black holes, you will:

Accepted Answer

A) be disappointed, because no electrons or other material particles can emerge from this region. 
B) find a stream of particles, which is independent of the mass of the black hole. 
C) find a stream of particles, which is greater for a more massive black hole. 
D) find a stream of particles, which is greater for a less massive black hole. 
A) be disappointed, because no electrons or other material particles can emerge from this region. 
B) find a stream of particles, which is independent of the mass of the black hole. 
C) find a stream of particles, which is greater for a more massive black hole. 
D) find a stream of particles, which is greater for a less massive black hole.

Question 4

What is the significance of the bending of a beam of light as it passes close to the Sun?

Accepted Answer

A) This behavior was predicted by Newton but not by Einstein. 
B) This behavior was predicted by Einstein but not by Newton. 
C) This behavior was predicted by both Newton and Einstein, but Einstein's theory gives the closer result. 
D) This behavior was predicted by neither theory, and it remains a mystery. 
A) This behavior was predicted by Newton but not by Einstein. 
B) This behavior was predicted by Einstein but not by Newton. 
C) This behavior was predicted by both Newton and Einstein, but Einstein's theory gives the closer result. 
D) This behavior was predicted by neither theory, and it remains a mystery.

Question 5

What is the Penrose process?

Accepted Answer

A) Objects grazing the ergoregion can gain energy from the black hole upon departing this region. 
B) Production of virtual pair particles at the event horizon can change the mass and charge of the black hole. 
C) Tidal forces can make the density of an object approach infinite values. 
D) Two satellites are placed in orbits in opposite directions to measure angular momentum. 
A) Objects grazing the ergoregion can gain energy from the black hole upon departing this region. 
B) Production of virtual pair particles at the event horizon can change the mass and charge of the black hole. 
C) Tidal forces can make the density of an object approach infinite values. 
D) Two satellites are placed in orbits in opposite directions to measure angular momentum.

Question 6

How would you measure the angular momentum of a black hole?

Accepted Answer

A) Place a satellite in orbit outside the event horizon and measure its period. 
B) Place two satellites in orbits in opposite directions and compare their periods. 
C) Release an object to fall into the black hole, and then watch to see if its path curves. 
D) Set a pole at rest outside the event horizon, pointing toward the black hole. If the pole begins to spin, the black hole has angular momentum. The amount is determined from the spin rate. 
A) Place a satellite in orbit outside the event horizon and measure its period. 
B) Place two satellites in orbits in opposite directions and compare their periods. 
C) Release an object to fall into the black hole, and then watch to see if its path curves. 
D) Set a pole at rest outside the event horizon, pointing toward the black hole. If the pole begins to spin, the black hole has angular momentum. The amount is determined from the spin rate.

Question 7

To "spin up" the rotation of a neutron star, infalling material from the binary companion impacts the surface at half the speed of light. Suppose the infalling material includes radioactive particles with a half-life T0 measured when the particle is at rest. What is the half-life of these particles measured by an observer on the neutron star?

Accepted Answer

A) 0.5 T0 
B) 0.87 T0 
C) 1.15 T0 
D) 2 T0 
A) 0.5 T0 
B) 0.87 T0 
C) 1.15 T0 
D) 2 T0

Question 8

All the following events are likely to generate observable gravitational waves EXCEPT ONE. Which one is the exception?

Accepted Answer

A) merger to two neutron stars 
B) supernova explosion of very massive star 
C) merger of two black holes 
D) 1-M ? star falling into black hole 
A) merger to two neutron stars 
B) supernova explosion of very massive star 
C) merger of two black holes 
D) 1-M ? star falling into black hole

Question 9

During a stop on Jupiter's satellite Europa to investigate a possible liquid ocean under the ice, you spot a spaceship passing Europa at 97% of the speed of light. A person on the spaceship sees 2 s tick past on your clock. How much time does this person see elapse on the clock on board her spaceship?

Accepted Answer

A) 0.48 s 
B) 8.2 s 
C) 33.8 s 
D) 0.12 s 
A) 0.48 s 
B) 8.2 s 
C) 33.8 s 
D) 0.12 s

Question 10

Suppose that a particular kind of subatomic particle lives on average for exactly 1.0 microsecond (1.0 × 10-6 s) before it decays, when this particle is created at rest in the laboratory. If a beam of such particles is created that travels at 97% of the speed of light as measured by a scientist standing beside the beam, what lifetime does the scientist measure for these particles?

Accepted Answer

A) 4.1 microseconds 
B) 0.24 microsecond 
C) 16.9 microseconds 
D) 0.06 microsecond 
A) 4.1 microseconds 
B) 0.24 microsecond 
C) 16.9 microseconds 
D) 0.06 microsecond

Question 11

There is an old joke about telling the police officer who stops you for running a red light that you were moving so fast that the light looked green. Take red to have a wavelength of 650 nm and green 500 nm. How fast WOULD you have to be moving (c = speed of light)? Is this relativistic?

Accepted Answer

A) 64% of c; yes 
B) 15% of c; no 
C) 97% of c; yes 
D) c/1000; no 
A) 64% of c; yes 
B) 15% of c; no 
C) 97% of c; yes 
D) c/1000; no

Question 12

The first pulsar was discovered by:

Accepted Answer

A) the Hubble Space Telescope, soon after it was launched, in 1990. 
B) Johannes Kepler, in 1604. 
C) an English graduate student, Jocelyn Bell, in 1967. 
D) the Astronomer Royal in Newton's time, Sir Edmund Halley, in 1606. 
A) the Hubble Space Telescope, soon after it was launched, in 1990. 
B) Johannes Kepler, in 1604. 
C) an English graduate student, Jocelyn Bell, in 1967. 
D) the Astronomer Royal in Newton's time, Sir Edmund Halley, in 1606.

Question 13

Two neutron stars form a close binary system and orbit each other rapidly. If we watch this motion from a position in the plane of the binary orbits, we would expect to see evidence of:

Accepted Answer

A) both a Doppler shift and a gravitational redshift. 
B) a Doppler shift but not a gravitational redshift. 
C) a gravitational redshift but not a Doppler shift. 
D) neither a Doppler shift nor a gravitational redshift. 
A) both a Doppler shift and a gravitational redshift. 
B) a Doppler shift but not a gravitational redshift. 
C) a gravitational redshift but not a Doppler shift. 
D) neither a Doppler shift nor a gravitational redshift.

Question 14

A pole is lying on the ground outside a barn. The length of the pole is the same as the length of the barn. A person picks up the pole and runs toward the barn at 90% of the speed of light, with the pole pointing toward the barn (a very athletic person!). How long does the barn appear to be compared to the pole, as seen by the person running?

Accepted Answer

A) The barn appears to be 19% of the length of the pole. 
B) The barn appears to be 5.3 times longer than the pole. 
C) The barn appears to be 2.3 times longer than the pole. 
D) The barn appears to be 44% of the length of the pole. 
A) The barn appears to be 19% of the length of the pole. 
B) The barn appears to be 5.3 times longer than the pole. 
C) The barn appears to be 2.3 times longer than the pole. 
D) The barn appears to be 44% of the length of the pole.

Question 15

How are antiparticles and virtual particles related?

Accepted Answer

A) All antiparticles are virtual particles. 
B) All virtual particles are antiparticles. 
C) All virtual particle pairs include a particle and its antiparticle. 
D) All particle-antiparticle pairs are virtual pairs. 
A) All antiparticles are virtual particles. 
B) All virtual particles are antiparticles. 
C) All virtual particle pairs include a particle and its antiparticle. 
D) All particle-antiparticle pairs are virtual pairs.

Question 16

Which of the following would NOT be considered a possible mechanism for the production of a black hole with a mass of a few solar masses?

Accepted Answer

A) coalescence of a binary pair of dead stars that spiral into one another after losing rotational energy as gravitational radiation 
B) slow gravitational condensation of a massive gas cloud directly into a black hole 
C) accretion of mass onto a white dwarf or neutron star from the companion star in a binary star system 
D) one member of a binary star exploding as a Type II supernova, leaving a black hole 
A) coalescence of a binary pair of dead stars that spiral into one another after losing rotational energy as gravitational radiation 
B) slow gravitational condensation of a massive gas cloud directly into a black hole 
C) accretion of mass onto a white dwarf or neutron star from the companion star in a binary star system 
D) one member of a binary star exploding as a Type II supernova, leaving a black hole

Question 17

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

Accepted Answer

A) x ray 
B) visible 
C) radio 
D) a period of 1.337 s, corresponding to a very low wave frequency of 0.7479 Hz 
A) x ray 
B) visible 
C) radio 
D) a period of 1.337 s, corresponding to a very low wave frequency of 0.7479 Hz

Question 18

The opening illustration of Chapter 21 of Universe, 11th ed., depicts a rotating black hole with an accretion disk. Magnetic field lines connect the black hole with the disk. What, if anything, can be transferred between the rotating black hole and its accretion disk?

Accepted Answer

A) Particles and energy can be transferred, but only from the disk to the black hole, never from the hole to the disk. 
B) Particles and energy can be transferred in either direction. 
C) Rotational energy and angular momentum can be transferred from the black hole to the accretion disk. 
D) Nothing can be transferred in either direction. 
A) Particles and energy can be transferred, but only from the disk to the black hole, never from the hole to the disk. 
B) Particles and energy can be transferred in either direction. 
C) Rotational energy and angular momentum can be transferred from the black hole to the accretion disk. 
D) Nothing can be transferred in either direction.

Question 19

Suppose you discover a naked singularity without its surrounding event horizon. What effect would such an object have on the neighboring region of space?

Accepted Answer

A) The "black hole" would no longer be black and would probably be very bright. 
B) Without the shielding effect of the event horizon, the black hole's gravity would begin pulling in stars and, indeed, whole galaxies to merge with it. 
C) The singularity would probably be spinning rapidly, because any infalling material from the accretion disk would now reach the singularity after a short journey. 
D) The effects of a naked singularity are completely unpredictable. 
A) The "black hole" would no longer be black and would probably be very bright. 
B) Without the shielding effect of the event horizon, the black hole's gravity would begin pulling in stars and, indeed, whole galaxies to merge with it. 
C) The singularity would probably be spinning rapidly, because any infalling material from the accretion disk would now reach the singularity after a short journey. 
D) The effects of a naked singularity are completely unpredictable.

Question 20

Suppose that a large piece (e.g., 5 Mε) of purple, magnetized iron is rotating 5 times per day. If this object were able to collapse gravitationally to form a black hole, which one of the following properties could an outside observer measure for the matter inside the black hole?

Accepted Answer

A) magnetic field 
B) color 
C) rotation 
D) composition 
A) magnetic field 
B) color 
C) rotation 
D) composition

Exam 21: Stellar Remnants: Neutron Stars and Black Holes

How long does a short gamma ray burst (short GRB) typically last?

What would happen to the gravitational force on Earth if the Sun were to be replaced by a 1-Mε black hole?

If you look for electrons emitted from the vicinity of black holes, you will:

What is the significance of the bending of a beam of light as it passes close to the Sun?

What is the Penrose process?

How would you measure the angular momentum of a black hole?

All the following events are likely to generate observable gravitational waves EXCEPT ONE. Which one is the exception?

There is an old joke about telling the police officer who stops you for running a red light that you were moving so fast that the light looked green. Take red to have a wavelength of 650 nm and green 500 nm. How fast WOULD you have to be moving (c = speed of light)? Is this relativistic?

The first pulsar was discovered by:

Two neutron stars form a close binary system and orbit each other rapidly. If we watch this motion from a position in the plane of the binary orbits, we would expect to see evidence of:

How are antiparticles and virtual particles related?

Which of the following would NOT be considered a possible mechanism for the production of a black hole with a mass of a few solar masses?

What range in the electromagnetic spectrum was being observed when the first pulsars were discovered?

The opening illustration of Chapter 21 of Universe, 11th ed., depicts a rotating black hole with an accretion disk. Magnetic field lines connect the black hole with the disk. What, if anything, can be transferred between the rotating black hole and its accretion disk?

Suppose you discover a naked singularity without its surrounding event horizon. What effect would such an object have on the neighboring region of space?

Suppose that a large piece (e.g., 5 Mε) of purple, magnetized iron is rotating 5 times per day. If this object were able to collapse gravitationally to form a black hole, which one of the following properties could an outside observer measure for the matter inside the black hole?

Astronomy and the Universe

Knowing the Heavens

Eclipses and the Motion of the Moon

Gravitation and the Waltz of the Planets

The Nature of Light

Optics and Telescopes

Comparative Planetology I: Our Solar System

Comparative Planetology II: the Origin of Our Solar System

The Living Earth

Our Barren Moon

Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

Jupiter and Saturns Satellites of Fire and Ice

Uranus, Neptune, Pluto, and the Kuiper Belt: Remote Worlds

Asteroids, Comets, and Impacts

Our Star, the Sun

The Nature of the Stars

The Birth of Stars

Stellar Evolution: on and After the Main Sequence

Stellar Evolution: The Death of Stars

Our Galaxy

Galaxies

Quasars and Active Galaxies

Cosmology: The Origin and Evolution of the Universe

Exploring the Early Universe

The Search for Extraterrestrial Life

Filters

What would happen to the gravitational force on Earth if the Sun were to be replaced by a 1-M_ε black hole?

Suppose that a large piece (e.g., 5 M_ε) of purple, magnetized iron is rotating 5 times per day. If this object were able to collapse gravitationally to form a black hole, which one of the following properties could an outside observer measure for the matter inside the black hole?