1. Universe Tenth Edition
Roger Freedman • Robert Geller • William Kaufmann III
Universe Tenth Edition
Clicker Questions
Chapter 21
Black Holes

2. According to experiments, the speed of light
is the same for all observers independent of whether they or the light source are moving.
appears to be faster than 3 × 108 m/s if you are moving toward the light source.
appears to be slower than 3 × 108 m/s if the light source is moving toward you.
is 6 × 108 m/s if the relative motion between the source and the observer is 3 × 108 m/s.
is infinite.
Q21.1

3. According to experiments, the speed of light
is the same for all observers independent of whether they or the light source are moving.
appears to be faster than 3 × 108 m/s if you are moving toward the light source.
appears to be slower than 3 × 108 m/s if the light source is moving toward you.
is 6 × 108 m/s if the relative motion between the source and the observer is 3 × 108 m/s.
is infinite.
A21.1

4. Special relativity explains the phenomena of ______, whereas general relativity deals with the nature of ______.
light and electromagnetism / gravity.
gravity / light and electromagnetism.
accelerating objects / light and electromagnetism.
light and electromagnetism / accelerating objects.
small objects / large objects.
Q21.2

5. Special relativity explains the phenomena of ______, whereas general relativity deals with the nature of ______.
light and electromagnetism / gravity.
gravity / light and electromagnetism.
accelerating objects / light and electromagnetism.
light and electromagnetism / accelerating objects.
small objects / large objects.
A21.2

6. You are on a windowless train and cannot see outside
You are on a windowless train and cannot see outside. The ride is extremely smooth. Is it possible to make a measurement inside the train to determine whether you are moving or are stationary?
Yes. Drop an object and see if it falls vertically or is deflected backward.
Yes. Shine a light forward up the aisle and backward down the aisle and measure the difference in their speeds.
Yes. Throw one ball forward down the aisle and throw a second ball backward down the aisle. Then determine which one went further.
No. There is no experiment that you can do inside the train to determine whether the train is moving at constant speed or is stationary.
Q21.3

7. You are on a windowless train and cannot see outside
You are on a windowless train and cannot see outside. The ride is extremely smooth. Is it possible to make a measurement inside the train to determine whether you are moving or are stationary?
Yes. Drop an object and see if it falls vertically or is deflected backward.
Yes. Shine a light forward up the aisle and backward down the aisle and measure the difference in their speeds.
Yes. Throw one ball forward down the aisle and throw a second ball backward down the aisle. Then determine which one went further.
No. There is no experiment that you can do inside the train to determine whether the train is moving at constant speed or is stationary.
A21.3

8. A friend takes a ride on a spaceship to a distant star and returns to Earth. You and your friend were the same age when your friend left on the spaceship. When your friend returns she
will be the same age as you.
will be younger than you.
will be older than you.
will be two times older than you.
could be older or younger than you depending on the speed during the journey.
Q21.4

9. A friend takes a ride on a spaceship to a distant star and returns to Earth. You and your friend were the same age when your friend left on the spaceship. When your friend returns she
will be the same age as you.
will be younger than you.
will be older than you.
will be two times older than you.
could be older or younger than you depending on the speed during the journey.
A21.4

10. If light is emitted by an object in the intense gravitational field near a black hole, and is viewed by an observer far away from the object, the observer will find that
its frequency is decreased and its wavelength is redshifted because time passes more slowly in an intense gravitational field.
its frequency is increased and its wavelength is blueshifted because time passes more slowly in an intense gravitational field.
its frequency is decreased and its wavelength is redshifted because time passes more rapidly in an intense gravitational field.
its frequency is increased and its wavelength is blueshifted because time passes more rapidly in an intense gravitational field.
Q21.5

11. If light is emitted by an object in the intense gravitational field near a black hole, and is viewed by an observer far away from the object, the observer will find that
its frequency is decreased and its wavelength is redshifted because time passes more slowly in an intense gravitational field.
its frequency is increased and its wavelength is blueshifted because time passes more slowly in an intense gravitational field.
its frequency is decreased and its wavelength is redshifted because time passes more rapidly in an intense gravitational field.
its frequency is increased and its wavelength is blueshifted because time passes more rapidly in an intense gravitational field.
A21.5

12. According to general relativity, a beam of light bends as it passes close to a massive object because
the massive object exerts an electromagnetic force on the photons.
the photons exert an electromagnetic force on the massive object.
it follows the curvature of the space around the massive object.
the speed of light increases.
the speed of light decreases.
Q21.6

13. According to general relativity, a beam of light bends as it passes close to a massive object because
the massive object exerts an electromagnetic force on the photons.
the photons exert an electromagnetic force on the massive object.
it follows the curvature of the space around the massive object.
the speed of light increases.
the speed of light decreases.
A21.6

14. The Schwarzschild radius of a non-rotating black hole is the
distance from the center of a black hole to the point at which the escape velocity equals the velocity of light.
radius of the solid matter part of a black hole.
inner radius of the black hole’s accretion disk.
outer radius of the black hole’s accretion disk.
radius of the progenitor star of the black hole.
Q21.7

15. The Schwarzschild radius of a non-rotating black hole is the
distance from the center of a black hole to the point at which the escape velocity equals the velocity of light.
radius of the solid matter part of a black hole.
inner radius of the black hole’s accretion disk.
outer radius of the black hole’s accretion disk.
radius of the progenitor star of the black hole.
A21.7

16. Black holes can be detected by the X rays they emit
Black holes can be detected by the X rays they emit. How are these X rays produced?
Black holes are very hot and radiate X rays from within their event horizon.
In the accretion disk around the black hole, matter is moving rapidly enough that any light emitted is blueshifted to the X-ray range.
Friction within the accretion disk heats up matter to temperatures high enough that the matter radiates in the X-ray range.
The intense gravitational field causes electromagnetic frequencies to increase, shifting them into the X-ray range.
Q21.8

17. Black holes can be detected by the X rays they emit
Black holes can be detected by the X rays they emit. How are these X rays produced?
Black holes are very hot and radiate X rays from within their event horizon.
In the accretion disk around the black hole, matter is moving rapidly enough that any light emitted is blueshifted to the X-ray range.
Friction within the accretion disk heats up matter to temperatures high enough that the matter radiates in the X-ray range.
The intense gravitational field causes electromagnetic frequencies to increase, shifting them into the X-ray range.
A21.8

18. Cygnus X-1 is believed to be composed of what objects?
A black hole and a supergiant star of spectral class B
A black hole and a main-sequence star of spectral class G
A neutron star and a supergiant star of spectral class B
A black hole and a neutron star
A black hole and a collapsar
Q21.9

19. Cygnus X-1 is believed to be composed of what objects?
A black hole and a supergiant star of spectral class B
A black hole and a main-sequence star of spectral class G
A neutron star and a supergiant star of spectral class B
A black hole and a neutron star
A black hole and a collapsar
A21.9

20. What critical test must a non-luminous compact object pass before it is determined to be a black hole?
It must emit X-rays.
It must have an accretion disk.
It must have a mass greater than 3 solar masses.
It must have a mass less than 3 solar masses.
It must be an isolated object with no companion star.
Q21.10

21. What critical test must a non-luminous compact object pass before it is determined to be a black hole?
It must emit X-rays.
It must have an accretion disk.
It must have a mass greater than 3 solar masses.
It must have a mass less than 3 solar masses.
It must be an isolated object with no companion star.
A21.10

22. Which of the following statements about long-duration gamma ray bursters is incorrect?
These bursts are associated with objects that have very large redshifts.
These bursts appear to emanate from distant galaxies.
These bursts are correlated with supernovae.
These bursts may be due to an exotic type of supernova called a collapsar.
These bursts are found mostly in the plane of the Milky Way.
Q21.11

23. Which of the following statements about long-duration gamma ray bursters is incorrect?
These bursts are associated with objects that have very large redshifts.
These bursts appear to emanate from distant galaxies.
These bursts are correlated with supernovae.
These bursts may be due to an exotic type of supernova called a collapsar.
These bursts are found mostly in the plane of the Milky Way.
A21.11