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PHYSICS > ASTROPHYSICS > Flashcards

ASTROPHYSICS Flashcards

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Physics 101 flashcards AP® Physics flashcards
1
Q

what is the universe?

A

a large collection of billions of galaxies

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2
Q

what is a galaxy?

A

a large collection of billions of stars

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3
Q

what galaxy is our solar system in?

A

the Milky Way

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4
Q

what causes moons to orbit planets?

A

gravitational force

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5
Q

what causes planets to orbit the sun?

A

gravitational force

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6
Q

what causes artificial satellites to orbit the earth?

A

gravitational force

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7
Q

what causes comets to orbit the sun?

A

gravitational force

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8
Q

describe the orbit of a comet:

A
  • highly elliptical
  • causes speed to change as the distance from the sun changes
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9
Q

describe the orbit of a moon:

A
  • circular
  • the closer the moon is to the planet, the shorter the time it will take to orbit
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10
Q

describe the orbit of a planet:

A
  • slightly elliptical
  • orbit at different distances from the sun
  • orbit at different speeds
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11
Q

relationship between orbital speed, orbital radius and time period:

A

orbital speed= (2 x pie x orbital radius)/ time period

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12
Q

why does gravitational field strength vary?

A

the more mass an object has, the greater its gravitational field will be

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13
Q

P2 stage one for how we reached today:

A

THE BIG BANG
time begins and space is created

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14
Q

P2 stage two for how we reached today:

A

INFLATION
the universe ‘inflates’ in size very quickly

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15
Q

P2 stage three for how we reached today:

A

NUCLEOSYNTHESIS
the very lightest nuclei, like hydrogen and helium are formed, the temperature is one billion kelvin

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16
Q

P2 stage four for how we reached today:

A

RECOMBINATION
nuclei and electrons combine to make neutral elements, the cosmic microwave radiation is created

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17
Q

P2 stage five for how we reached today:

A

STAR FORMATION
clouds of gas begin to condense into stars, some of the heavier elements are created in their cores

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18
Q

P2 stage six for how we reached today:

A

GALAXY FORMATION
galaxies and clusters of galaxies begin to form, the first stars begin to die, creating heavier elements

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19
Q

P2 stage seven for how we reached today:

A

SOLAR SYSTEM FORMATION
our solar system is formed, it exists in the Milky Way galaxy, part of our local group of galaxies

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20
Q

P2 stage eight for how we reached today:

A

TODAY
the universe has existed pretty much how we see it now for the past 5 billion years

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21
Q

P2 how is cosmic microwave background radiation created?

A

RECOMBINATION
nuclei and electrons combine to make neutral elements, the cosmic microwave radiation is created

22
Q

P2 evidence in favour of the big bang theory (1):

A

everything in the universe is moving away from everything else, if we reverse the expansion, we find that everything started at one point (the Big Bang)

23
Q

P2 evidence in favour of the big bang theory (2):

A
  • 380,000 years after the Big Bang, protons and electrons combined to produce neutral hydrogen atoms, this radiated light
  • as the universe cooled and expanded, the wavelength of this energy was shifted into the microwave region of the EM spectrum
24
Q

P2 evidence in favour of the big bang theory (3):

A
  • the CMBR has stretched during expansion and cooling, so the universe must have been smaller and hotter in the past
  • today, we can detect the 1mm microwave radiation throughout the universe, the same in whichever direction we look.
25
Q

P2 what is redshift and blueshift?

A

because objects in space move quickly, their doppler shifts are measurable, by measuring the doppler shift we can measure how fast a galaxy is moving

26
Q

P2 what happens if a wave is moving relative to an observer?

A

there will be a change in the observed frequency and wavelength

27
Q

P2 equation relating to change in wavelength, reference wavelength, velocity of a galaxy and speed of light:

A

change in wavelength/ reference wavelength = velocity of a galaxy/ speed of light

28
Q

P2 what are star’s brightness represented by on a standard scale?

A
  • absolute magnitude
  • scale is centred 0
  • brighter stars have a negative absolute magnitude
  • dimmer stars ave positive absolute magnitude
29
Q

how does the red- shift in light relate differ at different distances from the earth?

A

The further away a galaxy is the greater its red-shift and hence the faster it is moving away from us

30
Q

what class of star is blue?

A

O

31
Q

what class of star is deep blue white?

A

B

32
Q

what class of star is blue white?

A

A

33
Q

what class of star is yellowish white?

A

G

33
Q

what class of star is white?

A

F

34
Q

what class of star is pale yellow orange?

A

K

35
Q

what class of star is light orange red?

A

M

36
Q

what colour star is the hottest?

A

Blue

37
Q

what colour star is the coolest?

A

light orange red

38
Q

what is a nebula?

A

a star begins its life as a cloud of gas and dust called a nebula

39
Q

Once a nebula is formed, …… causes the gas to condense, and it eventually gets hot and dense enough for fusion to begin. The star lives most of its life as a …….

A
  • gravity
  • main sequence star
40
Q

once the …….. runs out of fuel, it swells up to become a …….

A
  • main sequence star
  • red giant
41
Q

once a …… is formed, less massive stars become unstable and throw off their outer layers, leaving a small hot-white ember behind, this is called a ……

A
  • red giant
  • white dwarf
42
Q

more massive stars collapse and begin to fuse ……… into heavier elements, the balance between gravity and fusion shifts and eventually the star explodes into a ……..

A
  • helium
  • supernova
43
Q

after a ……., the lighter stars collapse inward. The nuclei and their individual nucleons are crushed into pure …. to create a ……… ……

A
  • supernova
  • neutrons
  • neutron star
44
Q

after a ……, the more massive stars continue collapsing inwards until they reach a point of …….. …….., creating a …….. ……

A
  • supernova
  • infinite density
  • black hole
45
Q

P2 where do main sequence stars go on a hertzsprung-russell diagram?

A

subtle s shape down the middle

46
Q

P2 where do white dwarfs go on a hertzsprung-russell diagram?

A

bottom left

47
Q

P2 where do giants go on a hertzsprung-russell diagram?

A

just above s line to the right

48
Q

P2 where do supergiants go on a hertzsprung-russell diagram?

A

above giants
top right

49
Q

how does red-shift of galaxies support the big bang theory?

A
  • the further the galaxy is fro earth, the greater the red shift
  • the greater the red sift, the faster the galaxy is moving away
  • speed of galaxies increases with increased distance
50
Q

what is absolute magnitude?

A
  • because stars exist at wildly different distances from earth, their brightness is represented on a standard scale, called absolute magnitude

PHYSICS (10 decks)

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