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GCSE Physics - For The Runners 😉 > P16 - Space > Flashcards

P16 - Space Flashcards

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1
Q

What is the Big Bang Theoty?

A

The theory that states the to begin with all the matter in the universe was concentrated into a single incredibly dense point. This began to enlarge rapidly in a hot explosion. The universe has been expanding ever since. Space, time, and matter were created in the big bang

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2
Q

What is a black dwarf?

A

A star that has faded out and gone cold

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3
Q

What is a black hole?

A

An object in space that has so much mass that nothing, not even light, can escape from its gravitational field

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4
Q

what is centripetal force?

A

The resultant force towards the centre of a circle acting on an object moving in a circular path

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5
Q

What is cosmic microwave background radiation (CMBR)?

A

electromagnetic radiation that has been travelling through space ever since it was created shortly after the Big Bang as gamma radiation, however the doppler effect has caused them to now appear as microwave radiation

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6
Q

What is dark matter?

A

Matter in a galaxy that cannot be seen. Its presence is deduced because galaxies would spin much faster if their stars were their only matter

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7
Q

What is main sequence?

A

The main sequence is the life stage of a star during which it radiates energy due to fusion of hydrogen nuclei in its core

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8
Q

What is a neutron star?

A

The highly compressed core of a massive star that remains after a supernova explosion

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9
Q

What is a protostar?

A

The concentration of dust clouds and gas in space that forms a star

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10
Q

What is a red giant?

A

A star that has expanded and cooled, resulting in it becoming red and much larger and cooler than it was before

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11
Q

What is a red supergiant?

A

A star much more massive than the sun will swell out after the main sequence stage to become a red supergiant before it collapses

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12
Q

What is red-shift?

A

Increase in the wavelength of electromagnetic waves emitted by a star or galaxy due to its motion away form the observer. The faster the speed of the star or galaxy, the greater the red-shift is

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13
Q

What is a supernova?

A

The explosion of a massive star after fusion in its core ceases and the matter surrounding its core collapses onto the core and rebounds in an explosion

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14
Q

What is a white dwarf?

A

A star that has collapsed from the red giant stage to become much hotter and denser

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15
Q

What is a planet?

A

A planet is an object in orbit around a star that has cleared their orbit of other objects

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16
Q

What are moons?

A

A body in orbit around a planet

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17
Q

What is a comet?

A

Frozen rocks that move around the sun in orbits that are elliptical in shape. These elliptical orbits take them far away from the sun. You can only see them when they return near the Sun because then they heat up so much that they emit light.

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18
Q

Why can you only see a comet when it is near the sun?

A

You can only see them when they return near the Sun because then they heat up so much that they emit light.

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19
Q

What are meteors?

A

Small bits of rock that burn up when they enter the earths atmosphere

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20
Q

What are minor (dwarf) planets?

A

Dwarf planets have not cleared their orbit of other objects.

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21
Q

What are asteroids?

A

Asteroids are objects too small and uneven to be planets, usually in near-circular orbits around the Sun and without the ice present in comets

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22
Q

Describe the birth of a star:

A

It begins with a large cloud of dust and gas in space known as a stellar nebula. The stellar nebula is pulled together by their gravitational attraction. As these clouds join, becoming more and more dense, a protostar is formed. As the protostar becomes denser it gets hotter, this energy causes lighter nuclei to fuse together, energy is released from this fusion reaction so the protostar gets even hotter. Getting hotter and brighter, it begins to shine, giving birth to a main sequence star. The outward force from the nuclear fusion balances the force of the star’s gravity

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23
Q

How does a planet form?

A

The star’s gravity pulls smaller amounts of dust and gas together, forming planets in orbit of the star

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24
Q

Explain how main sequence stars are stable, and how the star becomes unstable.

A

A main sequence star is stable as the forces within it are balanced. The force of gravity acts inwards trying to make the star contract, the outward force of radiation from the nuclear fusion in its core trying to make the star expand. Energy released in the core keeps the core hot, so the process of fusion continues. Radiation such as gamma radiation flows out steadily from the core in all directions. These forces stay in balance until most of the hydrogen nuclei have fused to form helium nuclei, this causes the star to become unstable as there are no more hydrogen nuclei for hydrogen fusion

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25
What force pulls the dust and gas together to form a protostar?
Gravitational attraction
26
State the 5 stages of the life cycle of a star the same size as our sun:
* Protostar * Main Sequence Star * Red Giant * White Dwarf * Black Dwarf
27
State the 5 stages of the life cycle of a star the much bigger than our sun:
* Protostar * Main sequence star * Red Super Giant * Supernova * Neutron star / Black hole
28
Explain why low mass stars remain in the main sequence for much longer than large mass stars
Stars with low masses remain in their main sequence stage for much longer, as their core is cooler than that of more massive stars, therefore fusion takes place at a slower rate
29
Explain the life cycle of a low-mass star:
* The star initially forms from a cloud of dust and gas known as a nebula * Gravitational attraction pulls the dust and gas closer together to form a protostar * When the protostar becomes dense enough, hydrogen fusion begins releasing large amounts of energy * The outward pressure of nuclear fusion outwards balances the force of gravity inwards. This is known as a main sequence star * As hydrogen begins to run out, the "main sequence" stage ends. The outer layers of the star swells into a red giant, it becomes red as the surface cools. However, the core continues to contract. Therefore fusion of helium and other elements occur. This means heavier elements (up to iron) are created in the core of a star * When fusion stops no more radiation is released and the star ejects its outer layer of dust and gas, leaving a hot, dense solid core known as a White Dwarf Star * As a white dwarf cools, it emits less and less energy. When it not longer emits a signifigant amount, it is called a black dwarf
30
Explain the life cycle of a high-mass star:
* The star initially forms from a cloud of dust and gas known as a nebula * Gravitational attraction pulls the dust and gas closer together to form a protostar * When the protostar becomes dense enough, hydrogen fusion begins releasing large amounts of energy * The outward pressure of nuclear fusion outwards balances the force of gravity inwards. This is known as a main sequence star * As hydrogen begins to run out, the "main sequence" stage ends. The outer layers of the star swells into a red supergiant, it becomes red as the surface cools. However, the core continues to contract. Therefore fusion of helium and other elements occur. This means heavier elements (up to iron) are created in the core of a star * The star contracts and expands several times before exploding in a supernova, forming elements heavier than iron and ejecting them into the universe to form new planets and stars * The exploding supernova throws the outer layers of dust and gas into space, leaving a very dense core called a neutron star, this is an extremely dense object made only of neutrons. However, if the star is massive enough, it will become a black hole instead of a neutron star, this is a super dense point in space with such a strong gravitational attraction that not even light can escape it
31
How are elements up to Iron formed?
Nuclear fusion in the core of a red giant / red supergiant
32
How are elements larger than iron formed?
Heavy elements larger than iron are formed during a supernova explosion. The enormous force of the collapse fuses small nuclei into nuclei bigger than iron nuclei. The explosion also scatters the elements throughout the universe
33
How is helium formed?
Helium is formed through hydrogen fusion in the core of a main sequence star
34
What are the 2 types of satellites?
* Natural Satellite (e.g. the moon) | * Artificial Satellite (e.g. a space telescope)
35
What is a satellite?
Anything that orbits a celestial body
36
What are the uses of artificial satellites?
* Communication * Photography * Navigation * Experimentation * Weather Predictions
37
What are the 2 types of orbits?
* Circular Orbit | * Elliptical Orbit
38
What orbit does the moon take around the earth?
Circular
39
What keeps objects in orbit around other bodies?
Objects orbit much larger bodies due to the force of gravity. The gravitational pull of the large body on the smaller object keeps it in orbit
40
What are geostationary satellites?
Geostationary satellites are satellites which orbit the earth once every 24 hours, this means they always face the same part of the earth, they are further away than other artificial satellites
41
What are polar orbits?
Polar orbits take the satellites over the Earth’s poles. The satellites travel very close to the Earth, so they must travel at very high speeds
42
Explain why objects orbiting another body have a constant speed but their velocity is constantly changing:
Objects orbiting another body in a circular orbit have a constant speed, however their direction is constantly changing, therefore their velocity is constantly changing. Therefore the object is constantly accelerating as their velocity is constantly changing
43
Explain why an object in orbit does not fall into the larger body?
The centripetal force of gravity accelerates the object towards the centre of the larger body, however the velocity of the object is at a right angle to the centripetal force, therefore the force of gravity only changes its direction, keeping it orbiting the larger body.
44
In which direction does centripetal force act?
Towards the centre of the circle
45
At what angle is the direction of the planets motion to the force of gravity exerted by the sun?
90*
46
What happens if a satellites is travelling too slowly for the radius of its orbit?
If the satellite travels too slow, then the gravitational attraction will be too strong , and the satellite will fall towards the Earth.
47
Why can an object not orbit too close to a planet with an atmosphere?
atmospheric drag would slow the object, causing it to fall into the planet's surface
48
What happens if a satellites is travelling too fast for the radius of its orbit?
If the satellite travels too fast, then the gravitational attraction between the Earth and the satellite is too weak to keep it in orbit. If this is the case, the satellite will move off into space.
49
Explain how the speed of a satellite must change for the satellite to continue orbiting if the orbit radius is decreased:
The speed of the satellite must increase as the force of gravity on the object is greater, therefore it must travel faster to prevent crashing into the surface of the body
50
Explain how the speed of a satellite must change for the satellite to continue orbiting if the orbit radius is increased:
The speed of the satellite must decrease as the force of gravity on the object is lower, therefore it must travel slower to prevent flying off into space
51
Explain how the orbit radius must change for the satellite to continue orbiting if a satellite orbits faster:
The orbit radius must decrease, this is because it requires a stronger gravitational pull to prevent flying off into space
52
Explain how the orbit radius must change for the satellite to continue orbiting if a satellite orbits slower:
The orbit radius must increase, this is because it requires a weaker gravitational pull to prevent crashing into the planet
53
What is a theory?
An attempt to explain phenomena in out universe. Theories cannot be proven, however they can be disproven. If a theory is disproven then we look for another explanation. If a theory gains evidence that supports it then it becomes strongly accepted by most scientists as the dominant theory
54
What time period does the Big Bang Theory explain?
the origin of the universe and the evolution of the universe from that point, it does not explain anything before the big bang
55
What causes scientists to discredit one theory in favour of another?
If new evidence / observation cannot be explained by one theory but can be explained by another
56
What are the advantages and disadvantages of using a balloon with dots on the outside to model the expanding universe?
Advantages: *It shows the expansion of space and shows how galaxies are moving apart Disadvantages: * Balloons can only stretch so far * There would be galaxies inside the balloon as well
57
Objects above what temperature emit EM waves?
0K / -273*C
58
What is the doppler effect?
The doppler effect states that is the source of a wave is still, then the wavelength and frequency will remain constant, however: * When a source moves toward an observer, the observed wavelength decreases and the frequency increases * When a source moves away from an observer, the observed wavelength increases and the frequency decreases
59
Describe how the relative speed of a star or galaxy effects the shift (red shift / blue shift)
If the relative speed is greater, the shift is greater
60
Explain what a galaxy showing blue shift can tell us about the galaxy:
The galaxy that is showing a blue shift is approaching the earth, this is because when a source moves towards an observer, the observed wavelength decreases and the frequency increases, causing the light to shift towards the blue end of the spectrum.
61
Explain what a galaxy showing red shift can tell us about the galaxy:
The galaxy that is showing a red shift is moving away from the earth, this is because when a source moves away from an observer, the observed wavelength increases and the frequency decreases, causing the light to shift towards the red end of the spectrum.
62
Explain how red shift and blue shift can be identified:
If you pass light through a gas some wavelengths of light will be absorbed by the gas, forming an "absorption spectrum". The absorption spectrum from distant stars can be compared to the spectrum of our sun, from this we can see which way the absorption lines have shifted and therefore whether red shift or blue shift has occurred.
63
Explain how red shift supports the Big Bang theory
Light spectra from different stars and from the edge of the universe show a red shift. This indicates that the universe is expanding and moving apart as when a source moves away from an observer, the observed wavelength increases and the frequency decreases. This causes red shift. This supports the Big Bang Theory as it indicates the universe if moving apart, therefore suggesting the universe began from a very small initial point which it has constantly expanded from
64
What was created in the Big Bang?
Space, time, and matter
65
What is the steady state theory?
The steady state theory says that the Universe has always existed, and that the Universe is expanding and constantly creating matter as the Universe expands.
66
Explain the differences between the Big Bang theory and steady state theory
The big bang theory states that the universe began at a single point and has constantly expanded from that point since exploding suddenly, all matter and energy in the universe has existed since that point. However the steady state theory states that the universe has no origin and has always existed, in steady state theory matter is constantly being created as it expands
67
What is the origins of CMBR?
Radiation produced during the Big Bang
68
How is the wavelength of CMBR likely to change over the next billion years?
It is likely to increase as the universe is constantly expanding, this means that red shift will occur causing the CMBR to have a longer wavelength
69
What does the future of the universe depend on?
The Density of galaxies
70
What are the 2 possible futures of the universe?
* The Big Yawn | * The Big Crunch
71
What is the Big Yawn?
If the density of the universe is less than a particular amount, then the universe will continue to expand at an ever increasing rate until the stars will die out and everything else with them
72
What is the Big Crunch?
If the density of the universe if more than a particular amount then it will stop expanding and start contracting
73
How is dark matter known to exist and what does the existence of dark matter mean?
Stars only account for a small amount of a galaxies mass. Astronomers know this because galaxies would spin much faster if their stars were the only matter in galaxies. The missing mass is through the be dark matter. The presence of dark matter would mean that the average density of the universe would be much bigger
74
What theory does red-shift support?
Both the big bang theory and steady state theory
75
What theory does CMBR support?
The Big Bang theory
76
What is causing galaxies to accelerate away from each other?
dark energy
77
Why is an orbiting object constantly accelerating?
It is experiencing a constant change in velocity.
78
How many planets are in our solar system?
8
79
Explain how a galaxies speed changes with distance and how this can be detected and what is suggests?
Galaxies further away from Earth are moving away faster. This could be detected as the absorption lines from these galaxies showed greater red shifts. This is true in whatever direction you look into space This indicates that galaxies are moving apart and the universe is expanding as when a source moves away from an observer, the observed wavelength increases and the frequency decreases (red shift occurs)
80
What is hubbles law?
a law stating that the red shifts in the spectra of distant galaxies are proportional to their distance.
81
describe the universe when it first began
The universe was extremely hot and dense
82
Why is peer review important?
Helps detect bias or inaccurate data

GCSE Physics - For The Runners 😉 (16 decks)

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