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Pro Physics > P16 > Flashcards

P16 Flashcards

1
Q

Give the life cycle of a star bigger than that of the Sun

A

Nebula→Protostar→Main sequence→Red super giant→Supernova→Neutron star or Black hole

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2
Q

What galaxy is our solar system in?

A

Milky Way

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3
Q

What type of body is the Sun?

A

A star

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4
Q

What type of force pulls together cloud of dust and gas to form protostars?

A

Gravity

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5
Q

What factor determines the type of lifecycle a star undergoes?

A

The size of the star

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6
Q

Which 2 phases do all the stars undergo?

A

1) Protostar phase
2) Main sequence phase

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7
Q

What is a black hole?

A

A place in space where gravity pulls so much that even light cannot get out

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8
Q

What is a supernova?

A

Large explosion at the end of a large star’s life

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9
Q

Give 3 examples of dwarf planets

A
  • Pluto
  • Ceres
  • Eris
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10
Q

How do stars become red giants?

A

Eventually, the hydrogen begins to run out. This means that the star collapses inwards, causing the temperature to increase. Helium nuclei fuse together to create heavier elements and the star expands to form a red giant.

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11
Q

Lifecycle of a star diagram

A
  • protostar
  • main sequence
  • red giant
  • white dwarf
  • black dwarf
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12
Q

What is red-shift?

A

An observed increase in the wavelength of light from distant galaxies

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13
Q

What does the Big Bang Theory suggest?

A

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

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14
Q

What is blueshift?

A

If an object moves towards an observer the wavelength of light decreases. This is known as blueshift as the light moves towards the blue end of the spectrum.

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15
Q

List the 3 main components of a nuclear reactor

A
  • Fuel rods
  • Control rods
  • Moderator
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16
Q

What is the role of the moderator in a nuclear reactor?

A

To slow down the neutrons so they are travelling at speeds which allow them to be absorbed by fissile nuclei and cause fission

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17
Q

How is the chain reaction in a fission reactor kept under control?

A
  • Control rods are positioned in between the fuel rods
  • The rate of fission is controlled by moving these rods up and down
  • The lower the rods are inserted, the slower the rate of fission
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18
Q

Explain why nuclear fusion is currently not a viable way to produce energy on Earth.

A

With current equipment/techniques, the energy required is greater than the energy produced, resulting in a net energy loss.

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19
Q

What are 4 potential benefits of fusion?

A

-Heavy hydrogen, the fuel for fusion, is easily available in sea water
-The product, helium, is a non-radioactive harmless gas.
-It doesn’t produce greenhouse gases
-The energy produced can be used to generate electricity

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20
Q

Deuterium + Hydrogen Nucleus —>

A

Tritium + Energy

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21
Q

What do stars initially form from?

A

A cloud of dust and gas

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22
Q

What is a nebula and what does it become?

A

A nebula is a cloud of dust and gas. The force of gravity pulls the dust and gas together to form a protostar.

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23
Q

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

A

Nuclear fusion reactions

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24
Q

What happens when hydrogen nuclei undergo nuclear fusion?

A

They form helium nuclei

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25
Q

What happens to a white dwarf as it cools down and emits less energy?

A

It becomes a black dwarf

26
Q

How are elements distributed throughout the universe?

A

Through a supernova

27
Q

What does red-shift provide evidence for?

A
  • Supports the Big Bang Theory
  • Shows that the universe is expanding
28
Q

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

A

Supernovae

29
Q

What 2 things can stars much bigger than the Sun, become at the end of their lifecycle?

A
  • Neutron star
  • Black hole
30
Q

What is a neutron star?

A

The core of a red giant which is so compressed that its protons and electrons become neutrons

31
Q

How are elements heavier than iron produced?

A

In a supernova

32
Q

What type of orbit does the Earth have around the Sun?

A

Eliptical

33
Q

What happens to the velocity to an object in an orbit?

A

The speed remains constant, but the velocity constantly changes due to the direction changing

34
Q

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

A

Dark matter and energy

35
Q

In the Sun, what process creates a force outwards, balancing the inward force of gravity?

A

Nuclear fusion

36
Q

What happens when the radius of an object in orbit increases?

A

Speed decreases

37
Q

What is the consequence of an uncontrollable chain reaction?

A

The rate of fission events become to high and result in the production of too much energy, leading to a nuclear explosion

38
Q

Where is heavy hydrogen found?

A

In the ocean

39
Q

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

A

Very high temperatures

40
Q

What two things can be said about a galaxy the further away it is?

A
  • The further away it gets, the faster it is moving
  • The further away a galaxy is, the greater the red-shift
41
Q

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

A

The rate of expansion was expected to occur at an ever slower rate due to the gravitational forces

42
Q

What is CMBR?

A

Cosmic Microwave Background Radiation
It is defined as leftover radiation from the Big Bang and has a low temperature of -270 C

43
Q

In which stage will a star be most dense?

A

Neutron star

44
Q

What are the most common elements found in a star within its main sequence?

A

Hydrogen and Helium

45
Q

Describe nuclear fusion

A

Joining of 2 atomic nuclei to form a larger one

46
Q

What term is used to describe nuclei in which fission can be induced through the absorption of slow neutrons?

A

Fissile nuclei

47
Q

Which type of nuclear reaction releases more energy?

A

Nuclear fusion

48
Q

Explain the difficulty of generating energy through nuclear fusion.

A

Fusion requires very high temperatures which in itself requires large quantities of energy and also requires casing which can withstand them.

49
Q

What is a heavy hydrogen atom?

A

A hydrogen atom with 1 proton and 1 neutron

50
Q

What is a terameter?

A

A length of one trillion (1012) meters.

50
Q

Hydrogen + a neutron —>

A

Heavy Hydrogen (deuterium) + Energy

51
Q

Give the life cycle of a star the same size as the Sun

A

Nebula
Protostar
Main sequence
Red giant
White dwarf
Black dwarf

52
Q

Which property of a star does the range of wavelengths depend on?

A

Temperature

53
Q

What is the heaviest element fused within the cores of the most massive stars?

A

Iron

54
Q

What form of energy do all fission products have?

A

Kinetic energy

55
Q

What happens to the radius of an orbit when a satellite’s speed increases?

A

The radius of its orbit decreases, as the satellite needs a greater force of gravity to prevent it flying off into space.

56
Q

Give two examples of artificial satellites

A
  • TV satellites
  • GPS satellites
57
Q

How many planets make up our solar system?

A

8

58
Q

How long do stars spend in the main sequence phase?

A

Several billion years

59
Q

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

A

A natural satellite

60
Q

What do the planets in our solar system orbit around?

A

The Sun

61
Q
A

Pro Physics (14 decks)

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