Module 4 : Universe Flashcards

0
Q

(Nuclear Reactions Part 1 : Nuclear Forces and Radioactivity)
Draw a diagram of an atom showing the location and charge of the subatomic particles, including proton, neutron, electron, and nucleon.

A
  • SEE PAPER
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1
Q

(Nuclear Reactions Part 1 : Nuclear Forces and Radioactivity)
Describe the general structure of an atom.

A
  • Atoms are made up of electrons, neutrons, and protons
  • Nucleus (center/heart) is made up of neutrons and protons
  • Electrons “float” about the nucleus
  • Atom has stable nuclei if it has the right balance of neutrons to protons and right amount of energy to remain unchanged for a long time
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2
Q

(Nuclear Reactions Part 1 : Nuclear Forces and Radioactivity)
How does electrical force affect protons in the nucleus of an atom?

A
  • repulsive force
  • like charges repel
  • opposite charges attract
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3
Q

(Nuclear Reactions Part 1 : Nuclear Forces and Radioactivity)
What is strong nuclear force, and what role does it play in the nucleus of an atom?

A
  • acts between all nucleons
  • very strong over extremely short distances
  • allows positively charged protons to remain closer together
  • like charge attracts
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4
Q

(Nuclear Reactions Part 1 : Nuclear Forces and Radioactivity)
What makes an atom radioactive? How do the strengths of the strong nuclear force and the electric force relate to whether an atom is radioactive?

A
  • an atom is radioactive when it has too many or not enough neutrons in the nucleus.
  • in bigger atoms, neutrons help strong nuclear force keep protons together, which helps with the stability.
  • electric force can cause protons to split apart causing the atom to become unstable which can lead to radioactive qualities
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5
Q

(Nuclear Reactions Part 1 : Nuclear Forces and Radioactivity)
Where does radiation come from?

A
  • a radioactive atom is an unstable atom and must transform to become stable
  • the transformation process releases an energy called radiation.
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6
Q

(Nuclear Reactions Part 2 : Fission and Fusion)

What do each of the letters in E=mc2 stand for?

A
  • energy = mass x speed of light squared

- key to understanding why/how energy is released in nuclear reactions

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7
Q

(Nuclear Reactions Part 2 : Fission and Fusion)

What happens during nuclear fission? What are some examples of where fission would occur?

A
  • one large nucleus splits into smaller nuclei
  • radioactive elements : uranium, plutonium
  • found in nuclear power plants, also in nuclear bombs
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8
Q

(Nuclear Reactions Part 2 : Fission and Fusion)
What happens to the mass per nucleon in an atom when it is split into smaller nuclei? How does the change in mass per nucleon relate to the equation E=mc2?

A
  • mass is converted to energy
  • mass per nucleon decreases
  • nucleon in uranium nucleus has more mass -> uranium nucleus fragments are now nuclei of atoms such as barium and krypton -> nucleon in uranium fragment has less mass
  • energy = change in mass per nucleon x speed of light squared which creates powerful nuclear reaction
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9
Q

(Nuclear Reactions Part 2 : Fission and Fusion)

What happens during nuclear fusion? What are some examples of where fusion would occur?

A
  • smaller nuclei are fused together to make a bigger nucleus

- thermonuclear fusion in stars - hydrogen, helium, carbon

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10
Q

(Nuclear Reactions Part 2 : Fission and Fusion)
How does the mass per nucleon change in nuclear fusion? How does the change in mass per nucleon relate the the equation E=mc2?

A
  • the mass decreases as energy is released
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11
Q

(Nuclear Reactions Part 2 : Fission and Fusion)

How are fusion and fission the same? How are they different?

A
  • lose mass per nucleon as they form larger elements
  • e = mc(squared)
  • release energy
  • fission : split atoms, strong nuclear force must be overcome
  • fusion : fuse atoms, electrical force must be overcome
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12
Q

(Nuclear Reactions Part 2 : Fission and Fusion)
Give examples of atoms that will likely undergo fusion or fission, and describe the circumstances that would allow these nuclear reactions to occur.

A
  • fusion :
    • In the sun, hydrogen burning initiates fusion fuse and leads to formation of helium
    • Once hydrogen is used up, helium will fuse into carbon
  • fission : radioactive decay
    uranium bombarded by fast moving particles and energetic electromagnetic radiation and splits into fragments sometimes the uranium will absorb a neutron and forms plutonium
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13
Q

(Stars Part 1 : Star Characteristics)

What is the general chemical composition of stars?

A
  • Composition depends on composition of its local neighborhood
  • A star’s composition changes over time
  • Approximate composition of the universe : Hydrogen - 70%, Helium - 30%, Other >1%
  • Sun’s composition :
    • 71% Hydrogen
    • 27% Helium
    • 1% Oxygen
    • .5% Carbon
    • .01% Silicon
    • .01% Nitrogen
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14
Q

(Stars Part 1 : Star Characteristics)

Explain how stars can differ in brightness and color.

A
  • the brightness of a star is due to how much energy a star is producing
  • the brightness also depends on how far it is from earth
  • the color of a star is an indication of the surface temperature
  • blue = hottest, brightest
  • yellow = middle
  • red = coolest
  • luminosity : total amount of energy released per second by an object
  • absolute magnitude : how bright a star appears if all stars were the same distance from earth
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15
Q

(Stars Part 1 : Star Characteristics)

What is the Hertzsprung-Russell (H-R) diagram?

A
  • a graph plotting the luminosity (absolute magnitude) vs surface temperature of stars
  • shows several regions of stars
  • most are on a band stretched diagonally across the diagram
  • band : main sequence stars
  • main sequence stars generate energy by fusing hydrogen to helium - bright and hot
  • upper right - red giants
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16
Q

(Stars Part 1 : Star Characteristics)

What information about a star is used to categorize them on the H-R diagram?

A
  • shows the relationship between the Stars’ absolute magnitude or luminosity, versus their spectral types or classifications and effective temperatures
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17
Q

(Stars Part 1 : Star Characteristics)
Make a sketch of the H-R diagram, labeling the basic groups of stars that it identifies (main sequence stars, red giants, supergiants, white dwarves). Where is the sun located on this diagram?

A
  • SEE PAPER

- The sun is located on the main sequence

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18
Q

(Stars Part 2 : Star Birth and Low Mass Star Death)

When does the thermonuclear fusion reaction start in the life cycle of a star?

A
  • At extremely high temperatures, atoms will achieve a high enough kinetic energy to overcome the electric force.
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19
Q

(Stars Part 2 : Star Birth and Low Mass Star Death)
Describe the specific atoms involved in fusion of stars. What is the difference between a hydrogen-burning star and a helium-burning star?

A
  • hydrogen, helium, carbon, iron, nickel
    (A) hydrogen-burning star : (this is how stars start off)
    • hydrogen burning stage in a star lasts for a period of a few million to 50 billion years, depending on the mass of the star
    • the more massive the star - the shorter life it has
    • hydrogen fuel is consumed to keep balance between the thermal pressure and gravity
    • when the hydrogen fuel runs out, gravity overtakes the thermal pressure and the star caves inward
    • the core contracts and causes the temperature to rise
      (B) helium-burning star :
    • once the temperature rises it gets high enough to start helium burning (fusion of helium to carbon)
    • the star then has shells, helium and carbon at the center, while hydrogen fuses to helium in adjacent shell
    • the energy increases and the star moves off the main sequence
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20
Q

(Stars Part 2 : Star Birth and Low Mass Star Death)

Describe the relationship between gravitational force and thermal energy from fusion in the life of a star.

A
  • what happens when thermal pressure decreases? The star will contract
  • What happens when thermal pressure increases? The star will expand
21
Q

(Stars Part 2 : Star Birth and Low Mass Star Death)

Describe the life cycle of our sun

A
  • Average star -> Red Giant -> Planetary Nebula -> White Dwarf
  • Step 1 : Hydrogen Burning Main Sequence Star
  • Step 2 : Helium Burning increases thermal pressure - Red Giant Star
  • Step 3 : Thermal pressure greatly exceeds gravity - Planetary Nebula
  • Step 4 : Hot, non fusing carbon core - White Dwarf
22
Q

(Stars Part 3 : High Mass Star Death)

Describe the life cycle of a star more massive than our sun.

A
  • we define a massive star as being a star with mass of about 10 times the mass of the sun and greater
  • starts as hot main sequence stars, can form elements as heavy as iron in their cores
  • nebula -> main sequence star ->red supergiant -> supernova -> becomes either neutron star or black hole
23
Q

(Stars Part 3 : High Mass Star Death)

What determines what a star will become at the end of its life?

A
  • the mass of a star determines if it will end as a neutron star or black hole
24
Q
(Stars Part 3 : High Mass Star Death)
Describe the characteristics of the following stars : 
(A) main sequence star
(B) red giant
(C) supergiant
(D) white dwarf
(E) neutron star
A

(A) main sequence star : generate energy by fusing hydrogen to helium, brightest and hottest stars are blue, while the coolest are dim
(B) red giant : stars that have entered one if the late phases in stellar evolution, after being in the main sequence for billions of years, red Giants used up
(C) supergiant :
(D) white dwarf : a small, dim, extremely dense star that has collapsed on itself and is in the final stages of its evolution
(E) neutron star : a small, extremely dense star composed of tightly packed neutrons formed by the welding if protons and electrons

25
Q

(Solar System Part 1 : Structure of Solar System)

List and describe each component of the solar system, in order, from the sun to the Oort Cloud.

A
  • Sun
    • Energy via nuclear fusion : 4 hydrogen -> 1 helium + energy
    • Hotter in the core
    • Methods of heat transfer : convection, radiation primary heat
    • Core (hottest region) radiation zone (pushes heat out) convection zone (liquid hot material reaches the surface)
  • Terrestrial Planets : Mercury, Venus, Earth, Mars
    • all have rocky, solid surfaces
  • Asteroid Belt
    • asteroids are too small to become planet, pebble sized to hundreds of miles in diameter
    • meteoroid tiny to Boulder sized rock, burn up as meteors
  • Jovian Planets : Jupiter, Saturn, Uranus, Neptune
    • all are gas giants
  • Kuiper Belt : Pluto and comets
  • Pluto orbits sun is 248 Earth years, spins once every 6.4 Earth days, smaller than Earth’s moon, made of rock and nitrogen ice, highly elliptical and tilted orbit, classified as a dwarf planet
  • The Oort Cloud : comprising many billions of comets
26
Q

(Solar System Part 2 : Planet Characteristics)
Describe the way planets orbit the sun. What is the shape of the path they take? How does distance from the sun relate to the time it takes a planet to orbit the sun?

A
  • Mercury : Orbits Sun in 88 days
  • Venus : Orbits Sun in 225 days
  • Earth : Orbits Sun in 365 days
  • Mars : Orbits Sun in 687 days
  • Jupiter : Orbits Sun in 11.8 Earth years
  • Saturn : Orbits Sun in 29.4 Earth years
  • Uranus : Orbits Sun in 84 Earth years
  • Neptune : Orbits Sun in 165 Earth years
  • all orbit on a elliptical plane around the sun
27
Q

(Solar System Part 2 : Planet Characteristics)

Describe how planets rotate. What exceptions are there to the pattern most planets follow?

A
  • all planets travel in elliptical orbits around the Sun
  • Mercury : Spins once every 58 days
  • Venus : Spins once every 243 days (and spins backwards)
  • Earth : Spins once every 24 hours
  • Mars : Spins once every 24 hours
  • Jupiter : Spins once every 10 hours
  • Saturn : Spins once every 10 hours
  • Uranus : Spins once every 17 hours (axis is tilted)
  • Neptune : Spins once every 16 hours
28
Q

(Solar System Part 2 : Planet Characteristics)

Compare and contrast terrestrial and Jovian planets

A
  • terrestrial planet : (Mercury, Venus, Earth) are small, solid, rocky, and dense
  • Jovian planet : (Jupiter, Saturn, Uranus, Neptune) are large gaseous planets, have many rings and satellites, and composed of mostly hydrogen and helium.
29
Q

(Studying the Universe : Big Bang Theory)

Define cosmology.

A
  • the study of the entire universe, it’s structure, origin, and development
  • Big Bang Theory
30
Q

(Studying the Universe : Big Bang Theory)

What is the Big Bang Theory?

A
  • universe formed approximately 13.7 billion years ago
  • idea that physical universe began with primordial explosion, marks beginning of space and time
  • universe originated from a point of infinite density
  • energy fluctuations resulted in a rapid expansion called cosmic inflation
31
Q

(Studying the Universe : Big Bang Theory)
Describe each of the following and explain how they support the Big Bang theory :
(A) Doppler red shift
(B) Hubble’s law
(C) cosmic microwave background radiation
(D) element abundance

A

(A) Doppler red shift :
- in light we get from galaxies is proof the universe is still expanding
- visible light is stretched out - meaning increased distance with us and other galaxies
(B) Hubble’s law :
- v (velocity) = H (Hubble’s constant) x d (distance of galaxy from Earth)
- the farther away the galaxy, the faster it is moving away
- happening in all directions, universe is expanding in all directions
(C) cosmic microwave background radiation :
- 1960s : Arno Penzias and Robert Wilson at Bell Labs found noise in signals
- faint microwave radiation that is a result of the universe cooling itself
- strong evidence for Big Bang
(D) element abundance :
- calculations show ratios of elements could only have been made in universe that began in hot sea of radiation and elementary particles
- formed during the cooling of the early universe
-75% visible universe is hydrogen, nearly 25% helium

32
Q

Quiz A

According to the mass-energy relationship (E=mc2), what happens to the mass per nucleon in a fusion reaction?

A
  • Mass converts to energy because the two hydrogen-2 nuclei reactants have more mass per nucleon than the nucleons in the resulting helium-4 nucleus.
  • A fusion reaction occurs because the nucleons in hydrogen-2 have more mass than the nucleons in the fused helium-4 nucleus. The lost mass is converted to energy in accordance with the mass-energy relationship (E=mc2)
33
Q

Quiz A

What is necessary to start a thermonuclear fusion reaction in the Sun?

A
  • Extremely high temperatures are needed to overcome the electrical repulsions between hydrogen-2 nuclei.
  • Thermonuclear fusion reactions require extremely high temperatures because the nuclei must have enough speed to overcome the exotically repulsion that exists between protons.
34
Q

Quiz A

What correctly describes a stable (non-radioactive) atom?

A
  • The strong nuclear force is stronger than the electrical force.
  • The strong nuclear force helps to hold the nuclei together, and the electrical force tends to cause nuclei to break apart. In a stable atom, the strong nuclear force is at least as strong as the electrical force, but both are present
35
Q

Quiz A

How does strong nuclear force differ from the electrical force?

A
  • The electrical force acts over much larger distances than the strong nuclear force
  • The strong force acts between nucleons and is critical for overcoming the electrical repulsion between the protons and holding the nucleus together. It only acts over very short distances and weakens as the nucleus becomes larger in size.
36
Q

Quiz A

What correctly lists the stages in the life cycle of a massive star (more than ten times the mass of our sun)?

A
  • Protostar, main sequence, red giant, gravitational collapse, supernova, black hole
  • Massive stars generate more heat energy when they collapse. When the physical pressure I’d neutrons pushing against each other stops a star’s contraction it explodes in a supernova and the remnant becomes a black hole.
37
Q

Quiz A

How does a star’s temperature affect its appearance?

A
  • Hot stars appear blue because they emit shorter wavelengths of light.
  • The surface temperature of a star is directly related to the frequency of the radiation it emits. Hot stars emit shorter wavelengths of radiation and appear blue.
38
Q

Quiz A

What correctly describes the difference between terrestrial and Jovian planets?

A
  • Jovian planets are less dense because they are large in volume and consist primarily of hydrogen and helium.
  • Terrestrial planets are dense, rocky, relatively small planets whereas the Jovian planets are low in density, gaseous, and very large. Terrestrial planets are found closer to the sun, whereas Jovian planets are found further from the sun.
39
Q

Quiz A

How is Venus different from Earth?

A
  • The temperature on the surface of Venus is much hotter than Earth due to the composition of Venus’ atmosphere.
  • Venus is similar to Earth in size, density, and distance from the Sun but it’s high percentage of atmospheric carbon dioxide traps infrared radiation and heats the surface to approximately 460 degrees Celcius.
40
Q

Quiz A

How does Hubble’s Law provide support for the Big Bang theory?

A
  • It shows the rate of expansion of the universe matches the speed predicted by the Big Bang theory.
  • Edwin Hubble observed the redshift of light from distant galaxies and devised a mathematical equation to determine the velocity of galaxies, supporting the on-going expansion of the universe as an after effect of Big Bang.
41
Q

Quiz A

In what type of star is hydrogen fusion occurring?

A
  • Main-sequence star

- Main-sequence stars generate energy through hydrogen fusion.

42
Q

Quiz B

What is the proportionality constant in the mass-energy relationship (E=mc2)?

A
  • speed of light squared

- The speed of light (c^2) is proportionality constant in the formula (E=mc2), where E = energy, and m = mass.

43
Q

Quiz B

Why is gravity important in thermonuclear fusion reactions in stars?

A
  • Contraction of matter due to gravity creates the high temperature needed to start the reaction.
  • The attraction of matter due to gravity causes an increase in temperature and pressure. The high temperatures can then overcome the electrical repulsion between the nuclei and start thermonuclear fusion.
44
Q

Quiz B

What statement is true about all nuclear reactions?

A
  • Einstein’s equation E = mc2 applies.
  • All nuclear reactions follow Einstein’s equations, E = mc2. With fission of large atoms and fusion of small atoms, matter in converted to energy. With fusion of large atoms, energy is converted to matter.
45
Q

Quiz B

How does the strong force affect two protons placed in close proximity?

A
  • It attracts the two protons.
  • The strong force attracts protons and neutrons whereas the electrical force would cause the two protons that are electrically charged to repel one another.
46
Q

Quiz B

How does the cycle of low and medium mass stars differ from high mass stars?

A
  • Low and medium mass stars become white dwarfs after losing their outer shells.
  • As low and medium mass stars accumulate carbon in their cores, their nuclear fuel becomes depleted and they longer undergo fusion. The outer layers of the star are carried away by solar wind leaving behind a cooling core, known as a white dwarf.
47
Q

Quiz B

Why does a star in the red giant stage appear red?

A
  • It’s surface temperature is relatively cool, emitting longer wavelengths of light.
  • The color of a star depends on the peak frequency of the radiation emitted from the surface. Cool stars emit longer wavelengths of radiation and appear red.
48
Q

Quiz B

What correctly lists the organization of the solar system?

A
  • Sun, terrestrial planets, main asteroid belt, Jovian planets, Kuiper Belt, Oort Cloud
  • The main asteroid belt separates the terrestrial and Jovian planets; the disk-shaped Kuiper Belt and spherical Oort Cloud surround the solar system.
49
Q

Quiz B

What correctly describes the characteristics of Saturn?

A
  • It is less dense than any other Jovian planets.

- Saturn is the least dense planet in the solar system.

50
Q

Quiz B

What statement correctly describes evidence that supports the Big Bang theory?

A
  • Measurements of the wavelength of cosmic background radiation match the expected value of 7.35 cm which is consistent with the value expected from a cooling universe produced by the Big Bang.
  • Radio receivers detected microwaves with wavelength of 7.35 cm coming to Earth from all directions and calculated that after the Big Bang the universe would have cooled to 2.7 K which would emit wavelengths matching 7.35 cm.
51
Q

Quiz B

Which planet has the shortest year (orbital period)?

A
  • Mercury
  • The closer a planet is to the sun, the shorter its orbital period. Mercury is the closest planet to the sun, so it has the shortest year (Mercury’s year is about 88 Earth days).