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AQA Physics - Triple Science🪐⚛️🧠 > Topic 16 - Space > Flashcards

Topic 16 - Space Flashcards

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1
Q

What is the Big Bang Theory?

A

The theory that the universe was created in an outburst of all of the matter and energy in out universe and that it has been expanding ever since.

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2
Q

What is a black dwarf star?

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 such a large amount of mass that nothing, even light, can escape from its gravitational field. Its centre is a singularity with infinite mass and density.

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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 emitted shortly after the Big Bang.

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6
Q

What is dark matter?

A

Matter in the galaxy that we cannot observe and has mot been accounted for. Its presence has only been deduced.

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7
Q

What is the main sequence of a star?

A

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.

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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 far larger and cooler than previously

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11
Q

What is a red supergiant?

A

A star much more massive than the Sun that will swell out after the main sequence stage to become a red supergiant before collapsing.

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12
Q

What is red-shift?

A

The increase in wavelength of electromagnetic waves emitted by a star or galaxy due to its motion away from us. The faster the speed of the star or galaxy, the greater the red-shift.

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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 on to the core and rebounds.

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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 moon?

A

A natural satelitte.

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16
Q

What is a star?

A

A fixed luminous point in the universe, which uses nuclear fusion as its power source.

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17
Q

What is a nebula?

A

A large cloud of dust and gas occupying space between stars.

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18
Q

What is a meteorite?

A

Asteroid that has landed on the surface of Earth.

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19
Q

What is a meteor?

A

Asteroid in the atmosphere.

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20
Q

What is an asteroid?

A

A clump of rocks in space.

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21
Q

What is a comet?

A

A clump of ice.

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22
Q

What is the order of planets from the sun?

A

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

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23
Q

What are the first 4 planets from the sun classified as?

A

Rocky planets.

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24
Q

What is between Mars and Jupiter?

A

The asteroid belt.

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25
Q

What are Jupiter and Saturn classified as?

A

Gas giants

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26
Q

What are Uranus and Neptune classified as?

A

Cold gas giants.

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27
Q

What are planets?

A

A celestial body in orbit of a star.

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28
Q

How is a protostar formed?

A

-Clouds of dust rock and gas exist in a nebula. Gas is drawn inwards by gravity. The collapsing cloud begins to rotate and flatten into a disc of gas and dust.

-The disc rotates faster pulling material inwards. The particles collide more often, the temperature in the centre and the hot dense core makes a protostar.

29
Q

How is a star formed from a protostar?

A

-When the protostar becomes hot enough, hydrogen nuclei begin fusing, producing the heavier helium element. The energy released causes it to shine.

30
Q

How did the planets form?

A

-The sun at the centre gave off heat, evaporating ice in the cloud and pushing away gas, leaving clumps of rock orbiting close to the sun.

-The clumps aren’t hot enough to become protostars but form planets or asteroids.

31
Q

How does the star enter the main sequence?

A

Radiation pressure pushing outwards from the fusion reaction becomes equal to the gravity pulling inwards, the forces are balanced and the star is stable.

32
Q

What is the Hertzsprung-Russell diagram?

A

A scatter plot of stars in the universe based on temperature, luminosity and magnitude.

33
Q

What happens to a star if it becomes a red giant?

A

The star cools and swells when becoming a red giant, this collapses into a very small, hot and dense celestial object called a white dwarf.

The core compresses to a very dense state containing only neutrons called a neutron star.

34
Q

What happens when a star becomes a red supergiant?

A

The star cools and swells to form a red supergiant, this collapses forming heavy elements then explodes in a supernova, the elements are scattered throughout the universe.

35
Q

What happens to a star in the end of its life if it is categorised as a massive star?

A

The gravity will be very strong when it condenses, so light cannot escape as it has become a black hole with a singularity of infinite mass and density at its centre.

36
Q

What is the life cycle of an average star?

A

Stellar Nebula –> Average Star –> Red Giant –> Planetary Nebula –> White Dwarf

37
Q

What is the life cycle for a massive star?

A

Stellar Nebula –> Massive Star –> Red Supergiant –> Supernova –> Neutron Star or Black Hole.

38
Q

What is instantaneous velocity?

A

Velocity at a specific time.

39
Q

What is a stable orbit?

A

An orbit around a celestial body that doesn’t change.

40
Q

What are the differences and similarities between natural and artificial satelittes?

A

Differences:
-Natural satelittes are not man made, artificial satelittes are.
Similarities:
They both orbit around objects of greater mass than themselves.

41
Q

Why is a satelitte orbitting around an object at constant velocity said to be constantly accelerating?

A

Since velocity is a vector, it has direction and magnitude so if you keep magnitude constant and change direction, it will accelerate.

42
Q

What is a geostationary satelitte?

A

A satelitte which orbits around the celestial body at the same speed over the same place throughout its orbit.

43
Q

What is a geosynchronous satelitte?

A

A satelitte that orbits a celestial body at the same speed with which it moves but not over the same place.

44
Q

What are Low Polar Orbit satelittes?

A

These satelittes are very close to Earth compared with Geostationary satelittes so images generated by them are much clearer and sharper. Small objects can be tracked and they are used for short term weather forecasting.

45
Q

What are geostationary satelittes used for?

A

-Observing a larger area of the Earth’s surface.
-Observing longer term weather patterns.
-TV and radio signals can be broadcast around Earth.

46
Q

What is the Doppler Effect?

A

The wavelength of waves changes when an object moves towards or away from you. When they come towards you they increase in frequency and decrease in wavelength and when they move away they do the opposite.

47
Q

How did Edwin Hubble theorise that the universe had and is expanding?

A

He looked through his telescope to find that distant galaxies had redshifted, so their distance from Earth must be increasing, therefore the universe is expanding.

48
Q

How did Edwin Hubble’s ideas support the Big Bang theory?

A

Since he indicated that the universe was expanding, if we reverse the clock it would indicate that it originated from a single point, which affirms the Big Bang Theory.

49
Q

What does the Big Bang Theory state?

A

The Universe is expanding after exploding from a very small and dense region.

Space, time and matter were created in the Big Bang.

50
Q

Apart from Hubble’s ideas, what was discovered in 1965 that affirmed the Big Bang Theory?

A

In 1965 scientists discovered lower energy microwaves radiated in all directions, called cosmic microwave background radiation. This can only be explained by the Big Bang.

51
Q

What are the three theories for how the universe will end?

A

Open Universe - endless expansion
Flat Universe - continued but slowing expansion
Closed Universe - The Big Crunch where it collapses into another Big Bang which repeats.

52
Q

What are gravity waves?

A

Waves of the intensity of gravity that are generated by accelerated masses of binary stars and other motions of gravitational masses and propagate from the source at lightspeed.

53
Q

What is Dark Energy?

A

Unexplained energy that we cannot observe.

54
Q

What is the order of planets from the sun?

A

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

55
Q

What happens during the main sequence of a star?

A

Energy released in the core keeps the core hot, so the process of fusion continues.

Radiation like gamma flows out steadily from the core.

The star is stable as the forcea are balanced. The fusion force outwards is equal to gravity pulling it inwards.

56
Q

What is the heaviest naturally known element?

A

Uranium

57
Q

How are heavier elements than iron, the heaviest element made in nuclear fusion, formed?

A

By supernovae, when gas and dust form elements like uranium or plutonium

58
Q

What will happen to the Sun in the future?

A

It is about 5000 million years old and will live for another 5000 million years.

The sun will turn into a red giant bigger than the orbit of Mercury.

59
Q

What happens after a supernova?

A

The core of a star compresses into a neutron star, an incredibly dense object made of only neutrons.

If the star is massive enough it can become a black hole. Which has such a strong gravitational field that not even light can escape it.

60
Q

Why is a satelitte in circular orbit around the Earth at constant speed said to be accelerating?

A

It is constantly moving at right angles and this movement in direction circularly is called an acceleration as velocity has both direction and magnitude.

61
Q

What happens to the satelitte as it orbits further away from the Earth?

A

The speed needed for it to stay in a circular orbit decreases. The force of gravity on a satelitte is weaker when the satelitte is further.

The longer the orbiting body takes to move around the orbit once.

62
Q

What is red shift?

A

When the colour of an object turns more red as it moves further away from you.

63
Q

What is blue shift?

A

When light waves are compressed together as an object moves towards you. The wavelength is reduced.

64
Q

What is the rule for red shift?

A

The faster a star or galaxy is moving (relative to you), the bigger the shift is.

65
Q

What is the Big Bang Theory?

A

The universe is expanding after an explosion from very small and extremely hot and dense region.

Space, time and matter were created in the Big Bang.

66
Q

What two pieces of evidence were there for the Big Bang initially!

A

There was a red-shift for distant galaxies, so they must have expanded away from a certain point.

Cosmic Microwave Background Radiation exists, which shows that there was an explosion at the beginning of the universe.

67
Q

What is dark matter?

A

Matter which we cannot account for and cannot see.

68
Q

What is dark energy?

A

Energy that we cannot account for.

69
Q

What theories are there for how the universe will end?

A

If the density of the universe is less than a certain amount, it will expand forever.

If the density of the universe is more than a particular amount, it will stop expanding and go into reverse.

Some think that with dark energy and matter we cannot accurately predict it,

AQA Physics - Triple Science🪐⚛️🧠 (30 decks)

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