Astro 5 Kudu UPDATED Exam Questions
and CORRECT Answers
How might fundamental forces (gravity, the weak force, the strong force) be affected by
extremely high temperatures? - CORRECT ANSWER - They become the same force.
What was the approximate mass composition of the universe just before stars began to form? -
CORRECT ANSWER - 75% Hydrogen, 25% Helium
What is surprising about the universe from the period observed using the cosmic microwave
background? - CORRECT ANSWER - The universe was smoother than expected.
What occurred about 380,000 years after the big bang? - CORRECT ANSWER - Electrons
merged with nuclei to form atoms.
About how long after the big bang were protons and neutrons able to merge together into nuclei?
- CORRECT ANSWER - 3 minutes.
How did the horizon of the visible universe in the early universe compare to that which we have
today? - CORRECT ANSWER - The horizon was smaller and got larger as time went on.
When talking about the early stages of the universe what does inflation refer to? - CORRECT
ANSWER - A period of rapid expansion of the universe soon after the big bang.
What is thought to be the cause of temperature variations in the cosmic microwave background?
- CORRECT ANSWER - Tiny quantum fluctuations in the early universe expanded to a
macroscopic size by inflation.
How has the universe changed as it has moved forward in time? - CORRECT ANSWER -
It has become cooler and less dense.
,What is the earliest time in the universe that we have a fairly strong understanding of? -
CORRECT ANSWER - 10^-27 seconds after the big bang.
Stars can only begin to fuse carbon once they reach what temperature? - CORRECT
ANSWER - 500 million K
Which element fuses into iron at the core of a star? - CORRECT ANSWER - Silicon
When a high mass star first runs out of hydrogen in its core it causes the outer layers to change
dramatically, turning the star into... - CORRECT ANSWER - A red supergiant
How does the layering work in a late life, high mass star? - CORRECT ANSWER - Once
the fusion of one element ceases in the core of a star, the same kind of fusion will begin in a
layer around the core, inside of layers fusing smaller elements.
How does the rate of fusion of an element depend on the atomic mass of the element? -
CORRECT ANSWER - Heavier elements fuse more quickly than lighter elements.
A very massive star begins to collapse when the product of fusion is the element ... - CORRECT
ANSWER - Iron
What gives the matter in a supernova the energy to create such a huge explosion? - CORRECT
ANSWER - Interactions with huge amounts of neutrinos released from the super dense
core.
When a very high mass star (>25 Msun) collapses, what can it become? - CORRECT
ANSWER - A black hole
What is the name for the expanding material left over from the explosion of a high mass star? -
CORRECT ANSWER - A supernova remnant
, What is the most famous example of the expanding material left over from a large mass star
explosion? - CORRECT ANSWER - The Crab Nebula
What extremely powerful physical process generates the energy that powers the Sun at its core? -
CORRECT ANSWER - Fusion
Through what process is the heat generated at the Sun's core transferred to the outer layers of the
Sun? - CORRECT ANSWER - Convection
The particles from strong solar storms are powerful enough to destroy Earth's satellite
communications, and cause other damage that could take years to recover from. - CORRECT
ANSWER - True
Why is mass converted to energy in a fusion reaction? - CORRECT ANSWER - The
protons and neutrons in a helium nucleus are held together more tightly than in a hydrogen
nucleus.
Assume that 10% of the Sun's mass comprises of hydrogen in the core, where the temperature is
high enough for them to be converted to helium via the proton-proton chain. Calculate how much
energy is released in total in this process. Recall that the proton-proton chain has an efficiency of
0.71%, and give your answer in units of Joules. - CORRECT ANSWER - About
1.3×10^44 Joules
Based on your answer to the previous question, for approximately how long can the Sun shine
via the proton-proton chain? Recall that the Sun's luminosity is the rate at which it emits energy
released via the proton-proton chain. (About 1.3×10^44 Joules) - CORRECT ANSWER -
About 10^10 years
If the Sun were to suddenly produce Helium at its core at a decreased rate, observers on Earth
would would perceive the dimming of the Sun after a delay of 8 minutes and 20 seconds (the
time that it takes light to travel to Earth from the Sun). - CORRECT ANSWER - False
and CORRECT Answers
How might fundamental forces (gravity, the weak force, the strong force) be affected by
extremely high temperatures? - CORRECT ANSWER - They become the same force.
What was the approximate mass composition of the universe just before stars began to form? -
CORRECT ANSWER - 75% Hydrogen, 25% Helium
What is surprising about the universe from the period observed using the cosmic microwave
background? - CORRECT ANSWER - The universe was smoother than expected.
What occurred about 380,000 years after the big bang? - CORRECT ANSWER - Electrons
merged with nuclei to form atoms.
About how long after the big bang were protons and neutrons able to merge together into nuclei?
- CORRECT ANSWER - 3 minutes.
How did the horizon of the visible universe in the early universe compare to that which we have
today? - CORRECT ANSWER - The horizon was smaller and got larger as time went on.
When talking about the early stages of the universe what does inflation refer to? - CORRECT
ANSWER - A period of rapid expansion of the universe soon after the big bang.
What is thought to be the cause of temperature variations in the cosmic microwave background?
- CORRECT ANSWER - Tiny quantum fluctuations in the early universe expanded to a
macroscopic size by inflation.
How has the universe changed as it has moved forward in time? - CORRECT ANSWER -
It has become cooler and less dense.
,What is the earliest time in the universe that we have a fairly strong understanding of? -
CORRECT ANSWER - 10^-27 seconds after the big bang.
Stars can only begin to fuse carbon once they reach what temperature? - CORRECT
ANSWER - 500 million K
Which element fuses into iron at the core of a star? - CORRECT ANSWER - Silicon
When a high mass star first runs out of hydrogen in its core it causes the outer layers to change
dramatically, turning the star into... - CORRECT ANSWER - A red supergiant
How does the layering work in a late life, high mass star? - CORRECT ANSWER - Once
the fusion of one element ceases in the core of a star, the same kind of fusion will begin in a
layer around the core, inside of layers fusing smaller elements.
How does the rate of fusion of an element depend on the atomic mass of the element? -
CORRECT ANSWER - Heavier elements fuse more quickly than lighter elements.
A very massive star begins to collapse when the product of fusion is the element ... - CORRECT
ANSWER - Iron
What gives the matter in a supernova the energy to create such a huge explosion? - CORRECT
ANSWER - Interactions with huge amounts of neutrinos released from the super dense
core.
When a very high mass star (>25 Msun) collapses, what can it become? - CORRECT
ANSWER - A black hole
What is the name for the expanding material left over from the explosion of a high mass star? -
CORRECT ANSWER - A supernova remnant
, What is the most famous example of the expanding material left over from a large mass star
explosion? - CORRECT ANSWER - The Crab Nebula
What extremely powerful physical process generates the energy that powers the Sun at its core? -
CORRECT ANSWER - Fusion
Through what process is the heat generated at the Sun's core transferred to the outer layers of the
Sun? - CORRECT ANSWER - Convection
The particles from strong solar storms are powerful enough to destroy Earth's satellite
communications, and cause other damage that could take years to recover from. - CORRECT
ANSWER - True
Why is mass converted to energy in a fusion reaction? - CORRECT ANSWER - The
protons and neutrons in a helium nucleus are held together more tightly than in a hydrogen
nucleus.
Assume that 10% of the Sun's mass comprises of hydrogen in the core, where the temperature is
high enough for them to be converted to helium via the proton-proton chain. Calculate how much
energy is released in total in this process. Recall that the proton-proton chain has an efficiency of
0.71%, and give your answer in units of Joules. - CORRECT ANSWER - About
1.3×10^44 Joules
Based on your answer to the previous question, for approximately how long can the Sun shine
via the proton-proton chain? Recall that the Sun's luminosity is the rate at which it emits energy
released via the proton-proton chain. (About 1.3×10^44 Joules) - CORRECT ANSWER -
About 10^10 years
If the Sun were to suddenly produce Helium at its core at a decreased rate, observers on Earth
would would perceive the dimming of the Sun after a delay of 8 minutes and 20 seconds (the
time that it takes light to travel to Earth from the Sun). - CORRECT ANSWER - False
