Chapter 13

Question 1

Which of these objects has the smallest radius?
a 1.2 white dwarf
a 0.6 white dwarf
Jupiter

Answer 1

a 1.2M white dwarf

Question 2

Which of these isolated neutron stars must have had a binary companion?

 a pulsar inside a supernova remnant that pulses 30 times per second
 an isolated pulsar that pulses 600 times per second
 a neutron star that does not pulse at all

Answer 2

an isolated pulsar that pulses 600 times per second

Question 3

What would happen to a neutron star with an accretion disk orbiting in a direction opposite to the neutron star’s spin?

Answer 3

its spin would slow down

Question 4

From the viewpoint of an observer in the orbiting rocket, what happens to time on the other rocket as it falls toward the event horizon of the black hole?

Answer 4

Time runs increasingly slower as the rocket approaches the black hole.

Question 5

As the falling rocket plunges toward the event horizon, an observer in the orbiting rocket would see that the falling rocket __________.

Answer 5

slows down as it approaches the event horizon, and never actually crosses the event horizon

Question 6

you know that from afar we’ll never see the in-falling rocket cross the event horizon, yet it will still eventually disappear from view. Why?

Answer 6

Its light will become so redshifted that it will be undetectable.

Question 7

If you were inside the rocket that falls toward the event horizon, you would notice your own clock to be running __________.

Answer 7

at a constant, normal rate as you approach the event horizon

Question 8

If you were inside the rocket that falls toward the event horizon, from your own viewpoint you would __________.accelerate

Answer 8

accelerate as you fall and cross the event horizon completely unhindered

Question 9

Which of these objects has the largest radius?

 a 1.2 white dwarf
 a 1.5 neutron star
 a 3.0 black hole

Answer 9

1.2 M white dwarf

Question 10

Which of these things has the smallest radius?
a 1.2 white dwarf
the event horizon of a 3 black hole
the event horizon of a 10 black hole

Answer 10

the event horizon of a 3M black hole

Question 11

What would happen if the Sun suddenly became a black hole without changing its mass?

Answer 11

Earth’s orbit would not change

Question 12

How would a flashing red light appear as it fell into a black hole?

Answer 12

Its flashes would shift to the infrared part of the spectrum.

Question 13

Which of these black holes exerts the weakest tidal forces on an object near its event horizon?
a 10 Mblack hole
a 100M black hole
a 10^6 M black hole

Answer 13

a 10^6 M black hole

Question 14

Where do gamma-ray bursts tend to come from?

Answer 14

extremely distant galaxies