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Physics > Topic 8-Space physics > Flashcards

Topic 8-Space physics Flashcards

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1
Q

What galaxy is our solar system part of?

A

The Milky Way galaxy

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2
Q

How many planets orbit the sun

A

8

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3
Q

The sun lies at the centre of our solar system. What is the term used to describe this?

A

Heliocentric

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4
Q

What do the planets in our solar system orbit around and what type of body is it?

A

The planets orbit around the sun

The sun is a star

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5
Q

What type of force pulled together the cloud of dust and gas to form the Sun?

A

Gravitational force of attraction

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6
Q

Why might some planets rotate in the opposite direction or on a skewed axis to the other planets?

A

This may be due to past collisions throwing its axis balance

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7
Q

Why do some larger planets have rings?

A

Their gravitational field is so strong is attracts debris

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8
Q

What word is used to describe a cloud of dust and gas?

A

A nebula

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9
Q

What type of reactions take place at the start of a star’s life cycle as dust and gas is drawn together?

A

Fusion reactions

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10
Q

What factor determines the type of lifecycle a star undergoes?

A

The size of the star

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11
Q

Initially, Earth was at the centre, the planets, our moon, and the sun, orbited the Earth

What term is used to describe this?

A

“Geocentric” model

Everything orbited in perfect circles with a fixed background of stars

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12
Q

Which two phases do all stars of the same or greater size than the sun undergo?

A

Protostar phase

Main sequence phase

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13
Q

What do stars of a similar magnitude to the sun become at the end of their life-cycle?

A

A black dwarf

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14
Q

Why might some planets rotate in the opposite direction or on a skewed axis to the other planets?

A

It is due to past collisions throwing its axis off balance

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15
Q

Why do larger planets have rings?

A

Their gravitational field is so strong it attracts debris

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16
Q

What two things can stars much bigger than the sun become at the end of their lifecyle?

A

Neutron star

Black hole

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17
Q

What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?

A

Red giant

White dwarf

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18
Q

What two phases do stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole?

A

Red super giant

Supernova

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19
Q

What are produced during the fusion processes in a star?

A

All of the occurring elements

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20
Q

What condition is required for fusion reactions to occur in a star?

A

Very high temperatures

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21
Q

How are elements heavier than iron produced?

A

In a supernova

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22
Q

What type of nuclei fuse together to form heavier elements in a star

A

Hydrogen nuclei to form heavier elements

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23
Q

How are elements distributed throughout the universe?

A

Through the explosion of a massive star (super nova)

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24
Q

What allows planets and satellites to maintain circular orbits?

A

Gravity provides the gravitational force that acts as the object’s centripetal force

The presence of a centripetal force allows for the object to maintain its circular orbit

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25
Q

What type of satellite can a planet’s moon be described as?

A

A natural satellite

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26
Q

Give two examples of artificial satellites

A

TV satellites

Satellites used for satellite imaging

27
Q

Explain why for a stable orbit, the radius of orbit mist change if the speed changes

A

At higher speeds, the object requires a greater centripetal force

For a greater centripetal force, the gravitational force must increase

This is achieved by the radius of the orbit being reduced

28
Q

Explain how the of gravity acting on a satellite affects its speed and velocity

A

The force can alter its velocity since the direction is continually changing

It can’t cause a change of speed since there is no force component in the direction of motion

29
Q

What word is used to describe the sun’s position in our solar system?

A

Heliocentric

30
Q

What happens as the planets orbit the sun?

A

The gravitational force causes the planet to change direction constantly (it moves in a circle around the sun)

This means the velocity is always changing

Hence the force causes the planet to accelerate without increasing its speed

31
Q

Describe how a star is created

A

Dust and gas cloud is present in a galaxy

The gravitational attraction between the gas/dust particles draws them together

The cloud becomes more concentrated, as the particles get closer

The temperature and pressure of the cloud increases as the particles get pushed together

Eventually the pressure gets so great that the gas/dust particles are able to fuse together

32
Q

What is red shift?

A

An observed increase in the wavelength of light from distant galaxies

33
Q

What two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?

A

The further away a galaxy is, the faster it is moving

The further away a galaxy is, the greater the observed increase in wavelength

34
Q

What does red-shift provide evidence for?

A

Provides evidence that the universe is expanding

Supports the Big Bang Theory

35
Q

What does the Big Bang theory suggest?

A

The entire universe started from a very small, hot and dense region in space

36
Q

Compare the observed red-shift of two galaxies, one further away than the other

A

The galaxy that is further away is travelling faster

The observed red-shift is greater the further away it is

37
Q

What did scientists observe to provide evidence that the universe is expanding at an ever faster rate?

A

They observed supernovae, which suggested that galaxies are moving away at an ever faster rate

38
Q

Prior to observations of supernovae, what was believed about the rate of expansion of the universe and why?

A

The rate of expansion was expected to occur at an ever slower rate

It was thought that gravitational forces would cause this slowing down

39
Q

What two ideas could explain the universe’s ever increasing rate of expansion?

A

The existence of energy and mass that we can’t detect, known as dark matter and dark energy

These ideas are still being developed by scientists and are not yet fully understood

40
Q

The observations made by Hubble support the idea that the Universe is expanding.

This means that galaxies are continually moving away from each other and from the Earth.

Figure 2 shows a student using a balloon to model the idea of an expanding Universe.

Some dots, which represent galaxies, were marked on the balloon. The balloon was then inflated.

Give one strength and weakness of this model

A

Strength: as the balloon expands, the dots get further apart, representing the galaxies moving apart

Weakness: Dots are only on the surface of the balloon, galaxies are throughout the universe

Weakness: There is a limit to how far the balloon can expand

41
Q

Explain how the observation of galaxies moving away supports the Big Bang theory of the formation of the Universe

A

The furthest galaxies show the biggest red shift

This means that the furthest galaxies are moving the fastest

So the universe is expanding

This suggests that the Universe started from an initial point

42
Q

State one of a piece of evidence that supports The Big Bang theory of the formation of the universe

A

CMBR (cosmic microwave background radiation)

43
Q

Suggest what might cause scientists to stop supporting one theory and to start supporting an alternative theory

A

New evidence that supports/ disproves a theory

New evidence not supported by current theory

44
Q

Why are telescopes that detect different types of electromagnetic waves used to observe the universe?

A

Stars/galaxies emit different types of electromagnetic waves/radiation

45
Q

Describe The Big Bang theory

A

All matter comes from a single point.

A massive explosion sends matter outwards

46
Q

Suggest what scientists would do if new evidence were found that did not support The Big Bang theory

A

They would take the reliability of the evidence

47
Q

What is meant by red shift and what does it tell us about distant galaxies?

A

Longer wavelength waves

Galaxy moving away from the earth

48
Q

Explain why scientists believe that the solar system was formed from the material produced when earlier stars exploded

A

Solar system contains heavy elements and these heavy elements were formed by nuclear fusion at very high temperatures in a supernova

49
Q

Explain how the spectrum shift of the dark line towards the red side supports the theory that the universe began from a very small point

A

Line shifts towards red end of spectrum.

Wavelength appears to increase.

Galaxy is moving away from the earth

50
Q

What does the size of the red shift tell the scientists about the distance the Galaxy is from the earth?

A

The bigger the red shift, the further the Galaxy is from the earth.

51
Q

The light arriving from distant galaxies provide scientists have evidenced to support The Big Bang theory

Explain how

A

The lights shows a red shift which shows that galaxies are moving away

52
Q

What do scientists believe is the origin of cosmic microwave background radiation?

A

Radiation produced shortly after The Big Bang

53
Q

Why was the discovery of cosmic microwave background radiation so important to the scientists believing The Big Bang theory to be correct?

A

It can only be explained by The Big Bang

54
Q

The smaller masses may be attracted by the star and become…

A

Planets

55
Q

Our nearest star, the sun, is stable because the gravitational forces and the radiation pressure are….

A

Balanced

56
Q

Explain why the sun will not go through the supernova stage but the star Mira will

A

Only very massive stars become supernova

Mira is large enough but the sun is too small

57
Q

How is stars formed?

A

Dust and gas are pulled together by gravitational attraction

58
Q

State why a star is stable during the main sequence period of its life cycle

A

The forces within it (gravity and radiation pressure) are balanced

59
Q

Explain how stars like the sun were formed

A

They were formed from a giant cloud of gas and then condensed into a smaller volume by gravity

60
Q

Describe what will happen to the sun from the time the hydrogen is used up until the sun dies

A

Fusion decreases or stops

The gravitational forces no longer balances pressure

The sun expands and becomes a red giant it then cools and then becomes a white dwarf

61
Q

Explain what is meant by the term black hole

A

Mass with such a high density electromagnetic radiation/ light is pulled in

62
Q

Shortly after The Big Bang, hydrogen was the only element in the universe

Explain how the other elements came to be formed

A

They are formed by nuclear fusion of hydrogen to helium

Elements heavier than iron are only produced in a supernova

63
Q

Explain the difference between a protostar and a main sequence star

A

A protostar is at a lower temperature as fusion reactions have not started

64
Q

Explain why the velocity of the satellite changes as it orbits the Earth

A

Force of gravity causes the satellite to accelerate towards the Earth

The acceleration causes a change in direction

Velocity changes because direction changes

Physics (10 decks)

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