topic 8 - space physics

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31 Terms

1
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state what is in the solar system

  • the Sun

  • eight planets

  • and dwarf planets

  • that orbit the Sun

  • and moons

  • that orbit planets

2
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state what the Sun is

a star

3
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state what moons in the solar system are

natural satellites

4
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state what galaxy the solar system is part of

milky way galaxy

5
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state what formed the Sun

  • a nebula

  • pulled together

  • by gravitational attraction

6
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state nebula definition

cloud of dust and gas

7
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state what causes nuclear fusion to occur

  • when two light nuclei

  • collide at high speed

  • and join to create

  • a larger, heavier nucleus

8
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explain how the formation of a star causes fusion reactions

  • a star is formed when

  • it is hot enough

  • for hydrogen nuclei to undergo nuclear fusion

  • to make a helium nucleus

9
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explain how fusion reactions of stars leads to an equilibrium between the collapse of a star and the expansion of a star

  • gravitational attraction tends to collapse stars

  • radiation pressure from fusion reactions tend to expand stars

  • forces caused by gravitational attraction and fusion energy are balanced

10
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state what cycle a star goes through

life cycle

11
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state what a life cycle determines

the size of the star

12
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state the life cycle of a star the same size as the Sun

  1. nebula

  2. protostar

  3. main sequence star

  4. red giant

  5. white dwarf

  6. black dwarf

13
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state the life cycle of a star much bigger than the Sun

  1. nebula

  2. protostar

  3. main sequence star

  4. red super giant

  5. supernova

  6. neutron star/black hole

14
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state what fusion processes in stars produces

naturally occurring elements

15
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state where elements heavier than iron are produced

supernovas

16
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state what the explosion of a supernova does

distributes elements throughout the universe

17
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explain how fusion processes lead to the formation of new elements

  • majority of a star’s life, hydrogen nuclei fuse together to form helium nuclei

  • as a star runs out of hydrogen, other fusion reactions take place

  • forming the nuclei of other elements

  • forming elements lighter than iron in this way

  • the explosion of supernovas forms elements heavier than iron

  • as the explosion releases large amounts of energy and neutrons

  • all elements produced by fusion reactions in stars

  • gets thrown out and combine with with the neutrons

  • to form heavier elements

18
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state what allows planets and satellites to maintain their circular orbits

gravitational force

19
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state the similarities between planets, moons and artificial satellites

  • all orbit larger celestial bodies

  • due to gravitational forces

20
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state the differences between planets, moons and artificial satellites

  • artificial satellites are man-made

  • planets and moons are natural

21
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explain how in circular orbits, the force of gravity can lead to changing velocity but unchanged speed

  • velocity is a vector quantity

  • objects in orbit is accelerating

  • although its speed is constant

  • because its direction is constantly changing

22
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state what is needed for stable orbit

  • radius of the orbit must change

  • is speed changes

23
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state red shift definition

  • when wavelength of light

  • and the speed galaxies move at

  • increases in distant galaxies

24
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state what the red shift provides evidence for

  • provides evidence that space is expanding

  • and supports the Big Bang theory

25
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state what the big bang theory suggests

  • universe began from

  • a very small region

  • that was extremely hot

  • and dense

26
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describe what observations of supernovae from 1988 suggest

distant galaxies are receding even faster

27
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explain how red shift provides evidence for the big bang model

  • light spectrums from supernovae show that light from distant galaxies is redshifted

  • which suggests that the universe is expanding

  • as the Big Bang, a series of explosions

  • causes densely-packed matter to move out in all directions

  • and move further from the source of the explosion

  • before the Big Bang, galaxies were so close together that the entire universe was a single point

  • if the galaxies were originally grouped together and were then exploded, we would observe a similar red-shift effect

28
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state the doppler effect definition

  • a moving object will cause the wavelength of waves to change

  • the wavelength of the waves in front of the object decreases

  • and the frequency increases

  • the wavelength of the waves behind the object increases

  • and the frequency decreases

29
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state blueshift definition

  • when an object moves towards an observer

  • the wavelength of light decreases

  • as the light moves towards the blue end of the visible light spectrum

30
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explain how the change in each galaxy’s speed with distance is evidence of an expanding universe

  • light coming to the milky way galaxy from distant galaxies is redshifted

  • as the visible light spectrum is shifted towards the red end

  • indicating that galaxies are moving away from us

  • if galaxies are moving away from us, then the universe is expanding

  • the greater the distance of the galaxy, the greater the redshift

  • meaning that the further away the galaxy is, the faster it is moving away from us

31
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explain why there is still not much known about the universe

  • evidence from the rotation and motion of galaxies suggests that

  • there is much more matter in the universe than we are able to account for

  • this unseen matter is dark matter and its nature isn’t currently known

  • measurements of the expansion of the universe using supernovae suggest that the universe is expanding at a faster rate

  • it’s suggested that this is caused by dark energy pushing everything in the universe apart

  • if gravity was present everywhere in the universe, it would be expected that one day everything in the universe would get closer

  • which is the opposite of what we see

  • it’s suggested that dark energy may be counteracting gravitational forces in the universe