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Extra Credit Multiple Choice Questions
Chapters 10 − 12
Note: in all case one answer is better than all others ...
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Chapter 10 ***************************************************************
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1) As a result of gravity, a large cloud of hydrogen
and helium gas contracts and the gas gets denser
and denser. Then what happens at the center of
the gas cloud?
a) the temperature increases
b) the temperature decreases
c) the pressure increases
d) the pressure decreases
e) both a) and c)
video: Parallax in observing stars
1) In the video at the instant of the first appearance of the Sun on the
eastern horizon (called dawn) then the video says to look in the sky:
a) just above the sun
b) straight up (at 90−degrees from the direction to the sun)
c) directly opposite the sun (at 180−degrees from the sun)
d) a) or c) depending on the time of year
e) none of the above
2) In the video at the instant of the first appearance of the Sun on the
eastern horizon, then FROM THE DIRECTION YOU ARE TOLD TO LOOK the star
in the video is:
a) just to the left of your viewing direction
b) in your viewing direction
c) just to the right of your viewing direction
d) a) or c) depending on the time of year
e) none of the above
3) Then 6 months later (in the video) at the instant of the last vestige of
the Sun on the western horizon (at sunset), then FROM THE DIRECTION YOU
ARE TOLD TO LOOK the star in the video is:
a) just to the left of your viewing direction
b) in your viewing direction
c) just to the right of your viewing direction
d) a) or c) depending on the time of year
e) none of the above
video: Stellar Distance Using Parallax
1) To solve for the distance, d (in A.U.), to the nearby star(s) the
Khan Academy video uses the trigonometric relation:
a) tan( 90−theta ) = (1 A.U.)/d
b) tan( 90−theta ) = d/(1 A.U.)
c) cos( 90−theta ) = (1 A.U.)/d
d) cos( 90−theta ) = d/(1 A.U.)
2) In the video an example of the the angle theta (to a
nearby star) was:
a) 2.1353 x 10−5 degrees
b) 2.1353 x 10−4 degrees
c) 2.1353 x 10−3 degrees
d) 2.1353 x 10−2 degrees
e) 2.1353 x 10−1 degrees
3) In
a)
b)
c)
d)
e)
the video the distance to the star (measured by parallax) was:
1.52 light years
2.45 light years
3.32 light years
4.25 light years
5.12 light years
Chapter 11 ********************************************************************
video: Birth of Stars
Friday January 31, 2014
2) As a result of gravity the proto−star continues to
collapse until something happens in the core of the star
to stop the collapse?
a) hydrogen fusion "ignition"
b) helium fusion "ignition"
c) coulomb repulsion exceeds the gravitational pressure
d) electron degeneracy pressure exceeds the gravitational
pressure
e) neutron degeneracy pressure exceeds the gravitational
pressure
3) Following the fusion of two hydrogen (protons) the following
is said (in the video) to form:
a) di−hydrogen
b) deuterium
c) tritium
d) quartium
e) pentium
Chapter 12 *************************************************************
video: Becoming a Red Giant
1) As hydrogen fuses to helium, stopping the implosion of
the star, helium starts to build up in the core and
the video says:
a) the star is on the "main sequence"
b) fusion releases "a ton of energy"
c) the core begins to shrink
d) a) and b)
e) a) and b) and c)
2) As helium builds up in the core of the star then the video says
the core becomes:
a) opaque to energy transport
b) more and more massive
c) denser and denser
d) b) and c)
e) none of the above were said to happen
3) Once hydrogen is used up in the now helium core, the video says
hydrogen fuses in a "shell" around the core where:
a) the pressure is higher than when there was a hydrogen core
b) the hydrogen is fusing even faster than when there was a hydrogen core
c) fusion is occurring over a larger radius than when there was a
hydrogen core
d) a) and b)
e) a) and b) and c)
4) During the "red giant phase" our Sun is expected to increase in
diameter by:
a) 25 times
b) 50 times
c) 100 times
d) 250 times
e) 500 times
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5) In the Sun’s "red giant phase" the video says that
helium fuses predominantly into:
a) beryllium
b) carbon
c) oxygen
d) a) and b)
e) b) and c)
video: White and Black Dwarfs
1) Our Sun is now "brighter and hotter" than when it was formed
___________ years ago?
a) 4.4 to 4.5 billion
b) 4.5 to 4.6 billion
c) 4.6 to 4.7 billion
d) 4.7 to 4.8 billion
e) 4.8 to 5.0 billion
2) In
at
a)
b)
c)
d)
e)
the Sun’s "red giant phases", the Earth’s orbit will be
about:
1/4 times the Sun’s radius
1/2 times the Sun’s radius
1 times the Sun’s radius
3/2 times the Sun’s radius
2 times the Sun’s radius
3) As a result of gravity the helium core of a red giant
continues to collapse until something happens in the
core of the (1 solar mass) star to stop the collapse?
a) ignition of the hydrogen (in the shell just outside the
helium core) in a "hydrogen flash"
b) ignition of helium fusion (in the helium core) in a
"helium flash"
c) coulomb repulsion exceeds the gravitational pressure
d) electron degeneracy pressure exceeds the gravitational
pressure
e) neutron degeneracy pressure exceeds the gravitational
pressure
4) In the case of our Sun, the temperature in the core will
never get to the point for the fusing of:
a) hydrogen
b) helium
c) carbon
d) oxygen
e) c) and d)
5) In the video for a solar mass star it says that eventually
the remnant star is composed of an inert mass of:
a) hydrogen
b) helium
c) carbon and oxygen
d) a) and b)
e) b) and c)
video: Life Cycle of Massive Stars
1) In the video on the life cycle of MASSIVE stars the
mass of a MASSIVE star was defined to be GREATER
than:
a) 6 times the mass of the sun
b) 7 times the mass of the sun
c) 8 times the mass of the sun
d) 9 times the mass of the sun
e) 10 times the mass of the sun
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2) The lifespan of MASSIVE stars is ________ times
SHORTER than the lifespan of our Sun?
a) 10
b) 100
c) 1000
d) 10,000
e) 100,000
3) In the video it talks about fusing up to what isotope of
iron?
a) iron−54
b) iron−56
c) iron−57
d) iron−60
e) iron−62
4) Fusing of iron, to elements heavier than iron,
is a(n) _____________ reaction?
a) endothermic
b) exothermic
c) hydrothermic
d) astrothermic
e) mesothermic
video: Supernova (Supernovae)
[additional clarification in video: Supernova clarification]
1) Electron degeneracy pressure temporarily stabilizes
the collapse of the iron core of a super−massive star
until ____________ occurs (in the core of the star):
a) electron capture
b) neutron capture
c) electron decay
d) neutron decay
2) Electron degeneracy pressure temporarily stabilizes
the collapse of the iron core of a super−massive star
until "electron capture" occurs (in the core of the
star) to form a dense ball of:
a) neutrinos
b) neutrons
c) positrons
d) protons
e) alpha particles
3) During "electron capture" an enormous amount of energy
is released in the form of (energetic):
a) neutrinos
b) neutrons
c) positrons
d) protons
e) alpha particles
4) Nova (in supernova) comes from the _________ word for
"new"?
a) Arabic
b) Greek
c) Hittite
e) Latin
e) Sumerian
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5) In a supernova, the video said that material in the
outer shells of the star is expelled with velocities up to:
a) 1% the speed of light
b) 5% the speed of light
c) 10% the speed of light
d) 20% the speed of light
e) 50% the speed of light
6) In the video it is said that if the initial mass of the
star is GREATER than ____________ times the mass of the
sun then even neutron degeneracy pressure is not sufficient
and the remnant is a black hole:
a) 16 times
b) 17 times
c) 18 times
d) 19 times
e) 20 times
7) The supernova that resulted in the Crab Nebula is about how
far away?
a) 3,500 light years
b) 4,500 light years
c) 5,500 light years
d) 6,500 light years
e) 7,500 light years
8) The first light from supernova that resulted in the Crab Nebula
arrived at the Earth about ___________ years ago?
a) 500
b) 1,000
c) 1,500
d) 2,000
e) 2,500
9) The Khan Academy video gives the Crab Nebula as an example
of a supernova remnant with the current size of the
remnant nebula cloud of about ____________________ in
diameter?
a) 2 light years
b) 4 light years
c) 6 light years
d) 8 light years
e) 10 light years
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