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AQA GCSE PHYSICS 9-1 PAPER 1 > P16- Waves and the universe > Flashcards

P16- Waves and the universe Flashcards

1
Q

What process occurs in stars?

A

Nuclear Fusion

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2
Q

Why do we know that our solar system is the result of a supernova?

A

Elements have been found which are heavier than Iron

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3
Q

How was the Sun formed?

A

Sun formed at the centre of a spinning cloud of dust, gas, and rock due to the force of gravitational attraction
Sun’s heat evaporated the ice and drove the gas away from the inner solar system. leaving rocks behind
Rocky planets formed near the Sun
Gas Giants formed further away
Minor planets orbit beyond the gas giants

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4
Q

What are the gas giant planets?

A

Jupiter
Saturn
Uranus
Neptun

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5
Q

What are the rocky planets?

A

Mercury
Venus
Earth
Mars

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6
Q

Where is the asteroid belt located?

A

Between Mars and Jupiter

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7
Q

What force pulls together the gas, rocks and dust?

A

Gravitational attraction

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8
Q

When the clouds merge together, they become a what?

A

Protostar

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9
Q

As the protostar becomes denser, what happens to the particles and temperature?

A

They speed up

Temperature increases

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10
Q

When the protostar becomes denser, what energy transfer occurs?

A

Gravitational Potential into thermal energy

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11
Q

What happens when the protostar becomes hot enough?

A

The Hydrogen nuclei fuse

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12
Q

What is released by nuclear fusion and what happens to the star?

A

Energy is released

This causes the star to get hotter, brighter and starts to shine

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13
Q

Some objects may form which are far too small to become stars. What happens to them?

A

They can be attracted to a protostar to become planets orbiting the star

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14
Q

Stars such as the Sun radiate energy because of Hydrogen fusion in the core. What are these called?

A

Main Sequence Stars`

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15
Q

How long can main sequence stars maintain their energy output for?

A

Millions of years

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16
Q

How does radiation such as gamma radiation flow out from the core?

A

Steadily, in all directions

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17
Q

Why are stars stable?

A

Forces within it are balanced
Inwards force of gravity
Outwards force of radiation
These forces stay in equilibrium until most of the H nuclei have been fused to He nuclei

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18
Q

What is the heaviest known natural element and what is its half life?

A

Uranium - 4.5 Billion years

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19
Q

What has happened to elements heavier than Uranium?

A

They have decayed

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20
Q

What happens to stars smaller in size than our Sun?

A

They become a red giant

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21
Q

What happens to stars larger in size than our Sun?

A

They become a red supergiant

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22
Q

What happens to a red giant?

A

They become a white dwarf then a black dwarf?

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23
Q

What happens to a red supergiant?

A

They explode (die) as a supernova

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24
Q

What happens after a supernova?

A

A neutron star or black hole is formed, depending on its mass

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25
Q

Why can’t elements heavier than Iron be formed via nuclear fusion?

A

It requires too much energy

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26
Q

Around how old is the Sun?

A

5 Billion years old

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27
Q

In what shape does the Earth orbit the sun?

A

Circular

28
Q

In what shape do most other planets orbit the Sun?

A

Elliptical

29
Q

Give an example of a natural satellite?

A

The Moon

30
Q

What shape is the Moon’s orbit?

A

Circular

31
Q

Describe centripetal force in terms of the solar system

A

The force of gravity acting on a planet from the Sun, acts towards the centre of the Sun.
This force is the resultant force on the planet because no other forces act on it.
This is an example of centripetal force because it acts towards the centre of the circle

32
Q

What is changed by centripetal force?

A

A planet’s velocity

33
Q

What is true about the direction of motion of any planet?

A

In a circular orbit, it is at right angles to the direction of the force of gravity on it.

34
Q

In which direction does a planet in a circular orbit experience acceleration? Why?

A

Towards the centre of the circle

The resultant force on it acts towards the centre of the circle

35
Q

Explain why the speed of a planet in a circular orbit does not change.

A

The force on it is at right angles to its direction of motion
No work is done by the force on the planet
Kinetic energy and speed of the planet do not change

36
Q

What happens to satellites which orbit too close to the Earth? Why?

A

They gradually lose speed

Atmospheric drag of Earth’s upper atmosphere.

37
Q

What will happen when a satellite loses speed?

A

It will gradually spiral inwards until it hits the Earth

38
Q

A satellite in a circular orbit above the Earth’s atmosphere moves around the Earth at a constant height above the surface. True or False?

A

True

39
Q

What must happen for a satellite to stay in an orbit of a particular radius?

A

It has to move at a particular speed

The same is true for a planet orbiting the Sun in a circular motion.

40
Q

The further a planet is from the Sun, means what?

A

The less speed it needs to travel at to stay in a circular orbit
The longer the planet takes to make a full orbit

41
Q

Is the speed of a satellite in orbit changes, what must happen?

A

The radius of the orbit must change

42
Q

At what distance do communications satellites often orbit at?

A

36,000 km

43
Q

Describe the orbit of communications satellites

A

36,000km above the surface of the Earth
Orbits in the same direction as the Earth’s rotation
Geostationary - They stay above the same place.

44
Q

Uses of monitoring satellites?

A

They are fitted with TV cameras so:
Weather forecasting
Monitoring the environment

45
Q

Describe the orbit of monitoring satellites

A

Lower than geostationary satellites

Orbits the Earth once every two to three hours

46
Q

What galaxy is our solar system found in?

A

The milky way

47
Q

What can be used to split light into the colours of its spectrum?

A

A glass prism

48
Q

What is red shift?

A

The increase of the wavelengths of the light emitted by galaxies moving away

49
Q

What is the name of the shift of a galaxy moving towards you?

A

Blue shift

50
Q

In 1929, what did an astronomer discover, and who was he?

A

Edwin Hubble
Discovered:
Light from distant galaxies were red-shifted
The further a galaxy is, the larger its red shift

51
Q

What did the astronomer in 1929 conclude?

A

Distant galaxies are moving away from the Earth

The greater the distance a galaxy is from Earth, the greater the speed at which it is receding

52
Q

Describe the Big Bang Theory?

A

A theory which states that the universe has been forever expanding after exploding suddenly, from a very small and extremely hot and dense region.

53
Q

What was created in the Big Bang?

A

Space, Time and Matter

54
Q

Describe the Steady State Theory

A

A theory which states that the galaxies are being pushed apart by the matter entering the universe through “white holes” (the opposite of black holes)

55
Q

Until what year was the Steady State Theory widely accepted?

A

1965

56
Q

What evidence is there for the Big Bang?

A

High energy radiation is thought to have been emitted by the Big Bang
As the universe has been expanding, the radiation would have stretched into low level radiation

Experiments were formulated to detect this radiation.

57
Q

In 1965, what was concluded?

A

The existence of CMBR (Cosmic Microwave Background Radiation)
This could only be explained by the Big Bang Theory

58
Q

What is CMBR?

A

High energy gamma radiation which has stretched into Microwaves with the expansion of the universe.

59
Q

What do astronomers call the missing mass of the universe? Why?

A

Dark matter because it cannot be seen

60
Q

What does dark matter’s presence mean?

A

The average density of the universe is much larger than it would be if dark matter did not exist

61
Q

What would happen if the universe’s density was below a particular amount?

A

It will expand forever. The stars will die out, as will everything else. This is called the “Big Yawn”

62
Q

What would happen if the universe’s density was more than a particular amount?

A

The universe will stop expanding and fall back on itself - “The Big Crunch”

63
Q

What have astronomers concluded about the universe’s future?

A

It could be that the universe is heading for a Big Ride then a Big Yawn

64
Q

What is dark energy?

A

The name given to the energy thought to be pushing the galaxies apart

65
Q

Why can’t gravity be used to explain the acceleration/expansion of the universe?

A

It is an attractive force

AQA GCSE PHYSICS 9-1 PAPER 1 (16 decks)

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