Module 4 : Universe Flashcards Preview

From Flashcardlet > Module 4 : Universe > Flashcards

Flashcards in Module 4 : Universe Deck (52)
Loading flashcards...
0

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

- 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

1

(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.

- SEE PAPER

2

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

- repulsive force
- like charges repel
- opposite charges attract

3

(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?

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

4

(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?

- 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

5

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

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

6

(Nuclear Reactions Part 2 : Fission and Fusion)
What do each of the letters in E=mc2 stand for?

- energy = mass x speed of light squared
- key to understanding why/how energy is released in nuclear reactions

7

(Nuclear Reactions Part 2 : Fission and Fusion)
What happens during nuclear fission? What are some examples of where fission would occur?

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

8

(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?

- 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

9

(Nuclear Reactions Part 2 : Fission and Fusion)
What happens during nuclear fusion? What are some examples of where fusion would occur?

- smaller nuclei are fused together to make a bigger nucleus
- thermonuclear fusion in stars - hydrogen, helium, carbon

10

(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?

- the mass decreases as energy is released

11

(Nuclear Reactions Part 2 : Fission and Fusion)
How are fusion and fission the same? How are they different?

- 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

12

(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.

- 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

13

(Stars Part 1 : Star Characteristics)
What is the general chemical composition of stars?

- 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

14

(Stars Part 1 : Star Characteristics)
Explain how stars can differ in brightness and color.

- 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

15

(Stars Part 1 : Star Characteristics)
What is the Hertzsprung-Russell (H-R) diagram?

- 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

16

(Stars Part 1 : Star Characteristics)
What information about a star is used to categorize them on the H-R diagram?

- shows the relationship between the Stars' absolute magnitude or luminosity, versus their spectral types or classifications and effective temperatures

17

(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?

- SEE PAPER
- The sun is located on the main sequence

18

(Stars Part 2 : Star Birth and Low Mass Star Death)
When does the thermonuclear fusion reaction start in the life cycle of a star?

- At extremely high temperatures, atoms will achieve a high enough kinetic energy to overcome the electric force.

19

(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?

- 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

20

(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.

- what happens when thermal pressure decreases? The star will contract
- What happens when thermal pressure increases? The star will expand

21

(Stars Part 2 : Star Birth and Low Mass Star Death)
Describe the life cycle of our sun

- 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

(Stars Part 3 : High Mass Star Death)
Describe the life cycle of a star more massive than our sun.

- 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

(Stars Part 3 : High Mass Star Death)
What determines what a star will become at the end of its life?

- the mass of a star determines if it will end as a neutron star or black hole

24

(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) 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

(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.

- 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

(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?

- 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

(Solar System Part 2 : Planet Characteristics)
Describe how planets rotate. What exceptions are there to the pattern most planets follow?

- 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

(Solar System Part 2 : Planet Characteristics)
Compare and contrast terrestrial and Jovian planets

- 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

(Studying the Universe : Big Bang Theory)
Define cosmology.

- the study of the entire universe, it's structure, origin, and development
- Big Bang Theory