Question 1

What is the typical duration of a "long" gamma-ray burst?

Accepted Answer

A)  several days, indicating a size much smaller than the distance from Earth to the nearest star beyond the Sun 
B)  about a minute, indicating a source smaller than Mercury's orbit 
C)  up to about 1 hour, indicating a source less than half the size of the solar system 
D)  several hours, indicating a source somewhat larger than the solar system 
A)  several days, indicating a size much smaller than the distance from Earth to the nearest star beyond the Sun 
B)  about a minute, indicating a source smaller than Mercury's orbit 
C)  up to about 1 hour, indicating a source less than half the size of the solar system 
D)  several hours, indicating a source somewhat larger than the solar system

Question 2

If astronomers want to measure the mass of a star or a planet, they usually rely on the orbital motion of a satellite or binary companion. Which of these is the basis for a mass measurement of a solitary mass?

Accepted Answer

A)  time dilation 
B)  length contraction 
C)  gravitational redshift 
D)  geodesics 
A)  time dilation 
B)  length contraction 
C)  gravitational redshift 
D)  geodesics

Question 3

Which is the correct sequence for the end points of stellar evolution, in order of increasing mass?

Accepted Answer

A)  white dwarf, black hole, neutron star 
B)  white dwarf, neutron star, black hole 
C)  neutron star, black hole, white dwarf 
D)  black hole, neutron star, white dwarf 
A)  white dwarf, black hole, neutron star 
B)  white dwarf, neutron star, black hole 
C)  neutron star, black hole, white dwarf 
D)  black hole, neutron star, white dwarf

Question 4

A light wave is emitted from the accretion disk surrounding a black hole and moves toward the hole and away from an observer. This observer will see

Accepted Answer

A)  the beam of light moving faster than c as it accelerates toward the hole. 
B)  the beam of light slow down and stop as it reaches the event horizon. 
C)  that the wavelength of the light is gravitationally blueshifted and Doppler redshifted, and the two effects just cancel as the light reaches the event horizon. 
D)  that the wavelength of the light is gravitationally blueshifted as it falls toward the event horizon. 
A)  the beam of light moving faster than c as it accelerates toward the hole. 
B)  the beam of light slow down and stop as it reaches the event horizon. 
C)  that the wavelength of the light is gravitationally blueshifted and Doppler redshifted, and the two effects just cancel as the light reaches the event horizon. 
D)  that the wavelength of the light is gravitationally blueshifted as it falls toward the event horizon.

Question 5

By what method are MOST intermediate black holes thought to have formed?

Accepted Answer

A)  collapse of a supermassive star 
B)  collisions between stars in crowded environments 
C)  direct collapse of a gas cloud in the early universe 
D)  during the Big Bang 
A)  collapse of a supermassive star 
B)  collisions between stars in crowded environments 
C)  direct collapse of a gas cloud in the early universe 
D)  during the Big Bang

Question 6

What is the observed distribution of the shorter-living gamma-ray bursts in the sky?

Accepted Answer

A)  concentrated primarily along the plane of the Milky Way, indicating an origin in the Galaxy 
B)  uniform over the entire sky, indicating an origin outside the Milky Way 
C)  clumpy but not coinciding with any known galaxy clusters, indicating an origin in a new kind of astronomical object 
D)  clumpy, approximately coinciding with large clusters of galaxies such as the Coma cluster 
A)  concentrated primarily along the plane of the Milky Way, indicating an origin in the Galaxy 
B)  uniform over the entire sky, indicating an origin outside the Milky Way 
C)  clumpy but not coinciding with any known galaxy clusters, indicating an origin in a new kind of astronomical object 
D)  clumpy, approximately coinciding with large clusters of galaxies such as the Coma cluster

Question 7

The age of the universe is roughly 15 billion years, which is also the approximate evaporation time for a black hole with a mass of 1010 kg. What is the Schwarzschild radius of such a black hole?

Accepted Answer

A)  5.0*10-21 meters 
B)  1.5 *10-17 meters 
C)  6.3 *10-4 meters 
D)  1.5 au 
A)  5.0*10-21 meters 
B)  1.5 *10-17 meters 
C)  6.3 *10-4 meters 
D)  1.5 au

Question 8

Suppose a satellite were placed in orbit around (and very close to) a neutron star. Which theory would one need to use to describe how it moves?

Accepted Answer

A)  special theory of relativity 
B)  general theory of relativity 
C)  Kepler's laws 
D)  Newton's law of gravitation 
A)  special theory of relativity 
B)  general theory of relativity 
C)  Kepler's laws 
D)  Newton's law of gravitation

Question 9

In a TV tube, the picture is created by a beam of electrons that travels down the tube at a very high speed. What is the mass of one of these electrons, compared with an electron at rest?

Accepted Answer

A)  The mass of an electron is measured to be the same regardless of how fast it is moving. 
B)  The moving electron appears to have a smaller mass. 
C)  The electron appears to have a greater mass if one is in front of the tube (electrons approaching) and a smaller mass if one is standing behind the tube (electrons moving away). 
D)  The moving electron appears to have a greater mass. 
A)  The mass of an electron is measured to be the same regardless of how fast it is moving. 
B)  The moving electron appears to have a smaller mass. 
C)  The electron appears to have a greater mass if one is in front of the tube (electrons approaching) and a smaller mass if one is standing behind the tube (electrons moving away). 
D)  The moving electron appears to have a greater mass.

Question 10

One feature that distinguishes a black hole from all other objects in the universe is that

Accepted Answer

A)  the escape velocity from inside a black hole is greater than the speed of light. 
B)  a black hole emits large quantities of X-rays. 
C)  a black hole exceeds 3 solar masses. 
D)  the shape of the gravitational field of a black hole is different from that of an ordinary massive object, even at large distances from it. 
A)  the escape velocity from inside a black hole is greater than the speed of light. 
B)  a black hole emits large quantities of X-rays. 
C)  a black hole exceeds 3 solar masses. 
D)  the shape of the gravitational field of a black hole is different from that of an ordinary massive object, even at large distances from it.

Question 11

Theoretical physics predicts various types of black holes. Which of these is NOT one of them?

Accepted Answer

A)  primordial black holes: masses from a few grams to the mass of a planet 
B)  intermediate mass black holes: hundreds to thousands of solar masses 
C)  supermassive black holes: millions or billions of solar masses 
D)  supercluster black holes: billions of billions of solar masses 
A)  primordial black holes: masses from a few grams to the mass of a planet 
B)  intermediate mass black holes: hundreds to thousands of solar masses 
C)  supermassive black holes: millions or billions of solar masses 
D)  supercluster black holes: billions of billions of solar masses

Question 12

Which of these is NOT a test of general relativity but rather a test of special relativity?

Accepted Answer

A)  The length of a moving object decreases when observed by a stationary observer. 
B)  The wavelength of light increases as it leaves a region of gravitational field. 
C)  Light travels in a curved path in a gravitational field. 
D)  The perihelion position of Mercury's orbit precesses more quickly than is predicted by Newtonian theory. 
A)  The length of a moving object decreases when observed by a stationary observer. 
B)  The wavelength of light increases as it leaves a region of gravitational field. 
C)  Light travels in a curved path in a gravitational field. 
D)  The perihelion position of Mercury's orbit precesses more quickly than is predicted by Newtonian theory.

Question 13

In which of these locations would a clock run at its fastest rate?

Accepted Answer

A)  empty space, far from any planets or stars 
B)  Earth's surface 
C)  Jupiter's atmosphere 
D)  "weightless" environment on the Space Shuttle in orbit around Earth 
A)  empty space, far from any planets or stars 
B)  Earth's surface 
C)  Jupiter's atmosphere 
D)  "weightless" environment on the Space Shuttle in orbit around Earth

Question 14

Take two identical, nonrotating, 5-solar-mass black holes and place them side by side. Add 1 solar mass of pineapples to the left-hand one and 1 solar mass of uranium to the right-hand one (without changing the electrical charge or the rotation of either black hole). How will the two black holes differ?

Accepted Answer

A)  The right-hand black hole will have a stronger gravitational field because of the denser material inside it. 
B)  The two black holes will not differ at all. 
C)  The left-hand black hole will smell better. 
D)  The right-hand black hole will be radioactive, emitting alpha particles, electrons, and gamma rays into space. 
A)  The right-hand black hole will have a stronger gravitational field because of the denser material inside it. 
B)  The two black holes will not differ at all. 
C)  The left-hand black hole will smell better. 
D)  The right-hand black hole will be radioactive, emitting alpha particles, electrons, and gamma rays into space.

Question 15

A laborer repairing the clock tower on a space station orbiting a black hole accidentally drops the clock in such a way that it accelerates toward the black hole. What does the worker see while watching the clock?

Accepted Answer

A)  The hands of the clock keep normal time since time is absolute and the same everywhere. 
B)  The hands of the clock move slower and slower until they and the clock itself stop at the event horizon. 
C)  As the clock nears the event horizon, the hands begin to move randomly as time becomes jumbled near the black hole. 
D)  The hands of the clock move faster and faster until the clock plunges through the event horizon. 
A)  The hands of the clock keep normal time since time is absolute and the same everywhere. 
B)  The hands of the clock move slower and slower until they and the clock itself stop at the event horizon. 
C)  As the clock nears the event horizon, the hands begin to move randomly as time becomes jumbled near the black hole. 
D)  The hands of the clock move faster and faster until the clock plunges through the event horizon.

Question 16

As an observer is investigating a black hole from a safe distance, a rivet pops out of the tailfin on their spaceship and falls toward the black hole. Will the observer ever see the rivet enter the event horizon?

Accepted Answer

A)  Yes. However, it will be so blueshifted that the observer would need X-ray eyes to see it. 
B)  No. It will be compressed to zero size and disappear from sight before it reaches the event horizon. 
C)  Yes. The observer will see it fall faster and faster until it disappears as it falls through the event horizon. 
D)  No. It will appear to stop and hover forever before entering the event horizon. 
A)  Yes. However, it will be so blueshifted that the observer would need X-ray eyes to see it. 
B)  No. It will be compressed to zero size and disappear from sight before it reaches the event horizon. 
C)  Yes. The observer will see it fall faster and faster until it disappears as it falls through the event horizon. 
D)  No. It will appear to stop and hover forever before entering the event horizon.

Question 17

Which of these properties can NEVER be known about a black hole?

Accepted Answer

A)  type of material inside it 
B)  angular momentum (spin) 
C)  total amount of matter (the mass) inside it 
D)  net electric charge 
A)  type of material inside it 
B)  angular momentum (spin) 
C)  total amount of matter (the mass) inside it 
D)  net electric charge

Question 18

In a binary star system, an unseen component is found to have 8 solar masses. It would be visible if the system were a normal star, so it must be a collapsed object. Theoretical considerations declare that it must be a

Accepted Answer

A)  black hole. 
B)  neutron star. 
C)  white dwarf. 
D)  brown dwarf. 
A)  black hole. 
B)  neutron star. 
C)  white dwarf. 
D)  brown dwarf.

What is the typical duration of a "long" gamma-ray burst?

If astronomers want to measure the mass of a star or a planet, they usually rely on the orbital motion of a satellite or binary companion. Which of these is the basis for a mass measurement of a solitary mass?

Which is the correct sequence for the end points of stellar evolution, in order of increasing mass?

A light wave is emitted from the accretion disk surrounding a black hole and moves toward the hole and away from an observer. This observer will see

By what method are MOST intermediate black holes thought to have formed?

What is the observed distribution of the shorter-living gamma-ray bursts in the sky?

The age of the universe is roughly 15 billion years, which is also the approximate evaporation time for a black hole with a mass of 10¹⁰ kg. What is the Schwarzschild radius of such a black hole?

Suppose a satellite were placed in orbit around (and very close to) a neutron star. Which theory would one need to use to describe how it moves?

In a TV tube, the picture is created by a beam of electrons that travels down the tube at a very high speed. What is the mass of one of these electrons, compared with an electron at rest?

One feature that distinguishes a black hole from all other objects in the universe is that

Theoretical physics predicts various types of black holes. Which of these is NOT one of them?

Which of these is NOT a test of general relativity but rather a test of special relativity?

In which of these locations would a clock run at its fastest rate?

A laborer repairing the clock tower on a space station orbiting a black hole accidentally drops the clock in such a way that it accelerates toward the black hole. What does the worker see while watching the clock?

As an observer is investigating a black hole from a safe distance, a rivet pops out of the tailfin on their spaceship and falls toward the black hole. Will the observer ever see the rivet enter the event horizon?

Which of these properties can NEVER be known about a black hole?

In a binary star system, an unseen component is found to have 8 solar masses. It would be visible if the system were a normal star, so it must be a collapsed object. Theoretical considerations declare that it must be a

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

Exam 15: Black Holes: Matters of Gravity

What is the typical duration of a "long" gamma-ray burst?

If astronomers want to measure the mass of a star or a planet, they usually rely on the orbital motion of a satellite or binary companion. Which of these is the basis for a mass measurement of a solitary mass?

Which is the correct sequence for the end points of stellar evolution, in order of increasing mass?

A light wave is emitted from the accretion disk surrounding a black hole and moves toward the hole and away from an observer. This observer will see

By what method are MOST intermediate black holes thought to have formed?

What is the observed distribution of the shorter-living gamma-ray bursts in the sky?

The age of the universe is roughly 15 billion years, which is also the approximate evaporation time for a black hole with a mass of 1010 kg. What is the Schwarzschild radius of such a black hole?

Suppose a satellite were placed in orbit around (and very close to) a neutron star. Which theory would one need to use to describe how it moves?

In a TV tube, the picture is created by a beam of electrons that travels down the tube at a very high speed. What is the mass of one of these electrons, compared with an electron at rest?

One feature that distinguishes a black hole from all other objects in the universe is that

Theoretical physics predicts various types of black holes. Which of these is NOT one of them?

Which of these is NOT a test of general relativity but rather a test of special relativity?

In which of these locations would a clock run at its fastest rate?

A laborer repairing the clock tower on a space station orbiting a black hole accidentally drops the clock in such a way that it accelerates toward the black hole. What does the worker see while watching the clock?

As an observer is investigating a black hole from a safe distance, a rivet pops out of the tailfin on their spaceship and falls toward the black hole. Will the observer ever see the rivet enter the event horizon?

Which of these properties can NEVER be known about a black hole?

In a binary star system, an unseen component is found to have 8 solar masses. It would be visible if the system were a normal star, so it must be a collapsed object. Theoretical considerations declare that it must be a

Discovering the Night Sky

Gravitation and the Motion of the Planets

Light and Telescopes

Atomic Physics and Spectra

Exoplanets and the Formation of Planetary Systems

Formation of the Solar System

Earth and the Moon

The Other Terrestrial Planets

The Outer Planets

Vagabonds of the Solar System

The Sun: Our Extraordinary Star

Characterizing Stars

The Lives of Stars From Birth Through Middle Age

The Death of Stars

The Milky Way Galaxy

Galaxies

Quasars and Other Active Galaxies

Cosmology

Astrobiology

Filters

The age of the universe is roughly 15 billion years, which is also the approximate evaporation time for a black hole with a mass of 10¹⁰ kg. What is the Schwarzschild radius of such a black hole?