Chapter 14

The Chandrasckhar limit applies to which kinds of objects? a. neutron stars b. white dwarfs c. black holes d. massive main-sequence stars e. brown dwarfs

Which force or process is primarily responsible for creating a black hole? a. the strong nuclear force b. inertia c. gravity d. centrifugal force e. gas pressure

An observer moving at 90 percent of the speed of light \((0.9 c)\) would observe light around him to be moving at a. \(0.9 c\) b. \(0.1 c\) c, \(C_{1}\) d. \(0.81 c\) e. \(-0.1 c\)

Which of the following shares your reference frame while you're reading this book in your room? a. an astronaut on the Moon b. a geosynchronous satellite directly over your location c. an airplane 30,000 fcet up in the atmosphere traveling 400 miles per hour d. an Indy driver speeding on the course e. a person in an adjacent room of your residence

Two spaceships are moving in opposite directions, spaceship A traveling at \(0.9 c\) and spaceship \(\mathrm{B}\) traveling at \(0.95 c .\) Which of the following statements is true? a. \(B\) measures \(A\) moving at the speed of light. b. A measures B moving at the speed of light. c. Both measure light passing them at \(c\) d. Only A is actually moving. e. Only \(\mathrm{B}\) is actually moving.

Regarding special relativity and general relativity, which of the following is true? a. General relativity alone deals with gravity. b. Special relativity alone has \(c\) as a constant. c. Special relativity incorporates the effects of gravity. d. In special relativity alone, space and time are flexible. e. "General relativity" refers to objects in uniform motion.

Which of the following is true about gravitationally induced motion, according to general relativity? a. It is a result of an object's spin. b. It occurs as objects fall frecly following the curvature of space time. c. It does not follow Newton's laws. d. It is the same as uniform motion. e. It exists only near extremely massive objects.

Which of the following does/do not represent a successful test of relativity? Choose all that apply. a. the detection of muons created by cosmic rays b. the inference of gravity waves via binary pulsars c. the discovery of the wave nature of light d. weightlessness experienced by astronauts in space e. the accuracy of GPS devices

Which of the following is the densest? a. core of a \(1-M_{\text {sun }}\) star b. core of a \(100-M_{\text {sun }}\) star c. white dwarf d. neutron star e. singularity of a black hole

Which of the following is/are not measurable properties of black holes? Choose all that apply. a. mass b. elemental composition c. electric charge d. spin e. color

A patent clerk in a spaceship observes that time on the clock of an astronaut on a spaceship passing at \(0.25 \mathrm{c}\) runs slower than does time on his own clock. This phenomenon is called a. relativistic time dilation. b. time travel. c. gravitational time dilation. d. curvature of space-time. e. time warp.

As an object approaches the event horizon of a black hole, the light from it is observed to become a. longer in wavelength. b. shorter in wavelength. c. slower and slower. d. faster and faster. e. unchanged.

If you could be \(475 \mathrm{km}\) from the center of a \(200-M_{\mathrm{S}_{-}}\) black hole, which of the following would be true? a. You would see an accretion disk present. b. You would be orbiting at a constant speed. c. You would no longer be able to communicate with the rest of the Universe. d. You would be in the process of being accelerated into the black hole. e. You would be able to speed up to move away from the black hole.

Two spacecraft \((X 101 \text { and } X 102)\) with different velocities relative to each other pass in interstellar space. Which of the following cannor be true? a. \(X 101\) measures its own velocity as zero and measures a nonzero velocity for \(X 102\) b. \(X 102\) measures its own velocity as zero and measures a nonzero velocity for \(X_{1} 01\) c. Each measures both its own velocity and the velocity of the other as nonzero values. d. Both measure light passing them at exactly \(c\) e. A distant observer measures zero velocities for both.

Which of the following statements about Einstein's theory of gravity, compared with Newton's law of gravity, is true? a. It concluded that the effect of mass is less than expected, while that of distance is more than expected. b. It concluded that the effect of distance is less than expected, while that of mass is more than expected. c. It proved Newton's law entirely wrong. d. It made the use of Newton's law unnecessary. e. It showed that Newton's laws were a "limiting case" of general relativity that applied only when velocity and gravity were relatively low.

Which of the following statements is/are consistent with Einstein's special theory of relativity? Choose all that apply. a. There is no privileged frame of reference. b. The speed of light is constant, except when affected by relativistic time dilation. c. The speed of light is an upper bound to motion in the Universe. d. Time is not the same in all frames of reference. e. Space and time exist independent of each other.

True/False: Spaghcttification upon approaching the cvent horizon of a black hole occurs because gravity varies with distance from its source.

True/False: The 1919 solar eclipse provided support for relativistic Icngth contraction.

Describe the evidence for the existence of black holes.

What was the "luminiferous acther" believed to be, and why did physicists propose that it existed?

What is a frame of reference? What and who currently share your frame of reference?

Describe a situation in which the "addition of velocities" gives a correct result.

Why did Einstein conclude that space and time must be unified and measurements of each depend on an observer's frame of reference?

What is the twin paradox?

For what kinds of situations is special relativity relevant? For what kinds is general relativity relevant?

What are some of the effects that occur near black holes?

How does the detection of muons on the surface of Earth, after they are created high in Earth's atmosphere, provide evidence of special relativity?

What phenomenon defines the event horizon of a black hole?

What are the differences between supermassive black holes and stellar-mass black holes in terms of how they form?

What evidence suggests that massive black holes exist in galaxies?

Think about any movies or TV shows in which black holes have been portrayed. According to what you now know about black holes, were they reasonably accurate?

What is the mass, in \(M_{\mathrm{sw}}\), of a black hole whose Schwarzschild radius is \(990 \mathrm{km}\) ?

A black hole has a Schwarzschild radius of \(7 \times 10^{6} \mathrm{km}\). What is its mass, in kilograms?

What is the Schwarzschild radius, in meters, of a black hole whose mass is \(4 \times 10^{22} \mathrm{kg}\) ?

Sophia (on Earth) sees her twin sister, Stella, passing on her spacecraft at \(0.4 c\) and observes that Stella's clock runs slower than her own. Sophia's favorite movie runs 2 hours. How long by Sophia's clock, in hours, would the show run for Stella?

While riding on a jet from a distant space station at \(0.9 c\), the occupants of a spaceship take 35 minutes to prepare their dinner. How long, in minutes, does the dinner preparation take according to the clock of a NASA scientist on Earth who is observing the activity and the clock of the spaceship?

An American football game runs 60 minutes (not counting time-outs and commercials). You are on Earth observing a game being played aboard a starship traveling at \(0.79 c\). How many minutes does the game last on your clock?

An event takes 2 hours on the clock of a spacecraft at relativistic speed, and 8.4 hours on the clock of an observer on a nearby planet. At what speed is the craft traveling? (State your answer in terms of \(c .\) )