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Physics > Topic 8-Space physics > Flashcards

Topic 8-Space physics Flashcards

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
What type of satellite can a planet's moon be described as?
A natural satellite
26
Give two examples of artificial satellites
TV satellites Satellites used for satellite imaging
27
Explain why for a stable orbit, the radius of orbit mist change if the speed changes
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
Explain how the of gravity acting on a satellite affects its speed and velocity
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
What word is used to describe the sun's position in our solar system?
Heliocentric
30
What happens as the planets orbit the sun?
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
Describe how a star is created
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
What is red shift?
An observed increase in the wavelength of light from distant galaxies
33
What two things can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?
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
What does red-shift provide evidence for?
Provides evidence that the universe is expanding Supports the Big Bang Theory
35
What does the Big Bang theory suggest?
The entire universe started from a very small, hot and dense region in space
36
Compare the observed red-shift of two galaxies, one further away than the other
The galaxy that is further away is travelling faster The observed red-shift is greater the further away it is
37
What did scientists observe to provide evidence that the universe is expanding at an ever faster rate?
They observed supernovae, which suggested that galaxies are moving away at an ever faster rate
38
Prior to observations of supernovae, what was believed about the rate of expansion of the universe and why?
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
What two ideas could explain the universe's ever increasing rate of expansion?
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
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
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
Explain how the observation of galaxies moving away supports the Big Bang theory of the formation of the Universe
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
State one of a piece of evidence that supports The Big Bang theory of the formation of the universe
CMBR (cosmic microwave background radiation)
43
Suggest what might cause scientists to stop supporting one theory and to start supporting an alternative theory
New evidence that supports/ disproves a theory New evidence not supported by current theory
44
Why are telescopes that detect different types of electromagnetic waves used to observe the universe?
Stars/galaxies emit different types of electromagnetic waves/radiation
45
Describe The Big Bang theory
All matter comes from a single point. A massive explosion sends matter outwards
46
Suggest what scientists would do if new evidence were found that did not support The Big Bang theory
They would take the reliability of the evidence
47
What is meant by red shift and what does it tell us about distant galaxies?
Longer wavelength waves Galaxy moving away from the earth
48
Explain why scientists believe that the solar system was formed from the material produced when earlier stars exploded
Solar system contains heavy elements and these heavy elements were formed by nuclear fusion at very high temperatures in a supernova
49
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
Line shifts towards red end of spectrum. Wavelength appears to increase. Galaxy is moving away from the earth
50
What does the size of the red shift tell the scientists about the distance the Galaxy is from the earth?
The bigger the red shift, the further the Galaxy is from the earth.
51
The light arriving from distant galaxies provide scientists have evidenced to support The Big Bang theory Explain how
The lights shows a red shift which shows that galaxies are moving away
52
What do scientists believe is the origin of cosmic microwave background radiation?
Radiation produced shortly after The Big Bang
53
Why was the discovery of cosmic microwave background radiation so important to the scientists believing The Big Bang theory to be correct?
It can only be explained by The Big Bang
54
The smaller masses may be attracted by the star and become...
Planets
55
Our nearest star, the sun, is stable because the gravitational forces and the radiation pressure are....
Balanced
56
Explain why the sun will not go through the supernova stage but the star Mira will
Only very massive stars become supernova Mira is large enough but the sun is too small
57
How is stars formed?
Dust and gas are pulled together by gravitational attraction
58
State why a star is stable during the main sequence period of its life cycle
The forces within it (gravity and radiation pressure) are balanced
59
Explain how stars like the sun were formed
They were formed from a giant cloud of gas and then condensed into a smaller volume by gravity
60
Describe what will happen to the sun from the time the hydrogen is used up until the sun dies
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
Explain what is meant by the term black hole
Mass with such a high density electromagnetic radiation/ light is pulled in
62
Shortly after The Big Bang, hydrogen was the only element in the universe Explain how the other elements came to be formed
They are formed by nuclear fusion of hydrogen to helium Elements heavier than iron are only produced in a supernova
63
Explain the difference between a protostar and a main sequence star
A protostar is at a lower temperature as fusion reactions have not started
64
Explain why the velocity of the satellite changes as it orbits the Earth
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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