SMT 314 - Introduction to Cosmology » Fall 2020 » HW 14

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Question #1
Mass causes the surrounding space-time to ____________________.
A.   curve
B.   stop
C.   drop
D.   rotate
Question #2
The ________ (two words) of a black hole is its boundary, defining the region from within which nothing can escape (ignoring quantum effects).
A.   Schwarzschild radius
B.   event horizon
C.   stellar mass
D.   Einstein-Rosen Bridge
Question #3
A _____________ _________________ _______________ is a beam of highly energized photons that can erupt from the formation of a singularity. (three words)
A.   gamma-ray light
B.   ultra violet light
C.   emitting x-rays.
D.   gamma-ray burst
Question #4
According to Einstein's general theory of relativity, a black hole is completely described by its angular momentum, [a], and [b].
A.   density, mass
B.   speed. light
C.   radius, mass
D.   charge, mass
Question #5
All of the matter that falls into a black hole becomes concentrated in a very small volume (radius = 0) called a ______________.
A.   constant
B.   singularity
C.   sphere
D.   orbit
Question #6
Any object trying to orbit a black hole will necessarily be swallowed after orbiting just a few times.
A.   TRUE
B.   FALSE
Question #7
Direct observations of the trajectories of stars travelling near the center of our Milky Way Galaxy provide very strong evidence for the presence of a supermassive black hole, millions of times the mass of our Sun.
A.   FALSE
B.   TRUE
Question #8
Mathematically, it appears that simple, ideal, rotating black holes might connect our Universe to other universes, or to other distant parts of our Universe, but in reality matter probably cannot traverse the passage.
A.   FALSE
B.   TRUE
Question #9
How would we recognize the presence of a black hole?
A.   Find an astrometric binary with a massive companion.
B.   Identify an accretion disk emitting x-rays.
C.   Find star(s) orbiting a blank spot.
D.   All of these answers would work.
Question #10
The presence of a black hole in a galatic core can be inferred from:
A.   the diminished brightness of starlight in the galaxy core, relative to surrounding areas.
B.   the speeds of the stars near the core.
C.   the distance of the galaxy from the Milky Way Galaxy.
D.   the total mass of the galaxy.
E.   the color of the galaxy.
Question #11
Which one of the following statements about black holes is false?
A.   A black hole has an "event horizon" from which no light can escape, according to classical (i.e., non-quantum) ideas.
B.   Inside a black hole, matter is thought to consist primarily of iron, the end point of nuclear fusion in massive star.
C.   Near the event horizon of a stellar mass black hole, tidal forces stretch objects apart.
D.   A black hole that has reached an equilibrium configuration can be described entirely by its mass, electrical charge and amount of spin ("angular momentum").
Question #12
Which one of the following statements about stellar mass black holes is true?
A.   Most pulsars are thought to be rapidly rotating black holes.
B.   A stellar-mass black hole can suddenly brighten after swallowing a clump of gas in the surrounding accretion disk; the light comes out from inside the event horizon.
C.   Black holes are generally more massive than three solar masses because neutron degeneracy pressure can hold up smaller masses.
D.   Our Sun will become a black holes at the end of its life.

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