P8 - space physics Flashcards

1
Q

Which galaxy is our solar system part of?

A

The Milky Way galaxy.

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2
Q

How many planets make up our solar system?

A

Eight (plus the dwarf planets).

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3
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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4
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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5
Q

What word is used to describe a cloud of dust and

gas?

A

A nebula.

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6
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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7
Q

What factor determines the type of lifecycle a star undergoes?

A

The size of the star.

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8
Q

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

A
  1. Protostar phase

2. Main sequence phase

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9
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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10
Q

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

A
  1. Neutron star

2. Black hole

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11
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
  1. Red giant

2. White dwarf

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12
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
  1. Red super giant

2. Supernova

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13
Q

What are produced during the fusion processes in a

star?

A

All of the naturally occurring elements.

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14
Q

What condition is required for fusion reactions to

occur in a star?

A

Very high temperatures.

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15
Q

How are elements heavier than iron produced?

A

In a supernova.

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16
Q

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

A

Hydrogen nuclei fuse to form heavier

elements.

17
Q

How are elements distributed throughout the

universe?

A

Through the explosion of a massive star

supernova

18
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

19
Q

What type of satellite can a planet’s moon be

described as?

A

A natural satellite

20
Q

Give two examples of artificial satellites.

A
  1. TV satellites

2. Satellites used for satellite imaging

21
Q

Explain why for a stable orbit, the radius of orbit

must 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

22
Q

Explain how the force 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

23
Q

What is red-shift?

A

An observed increase in the wavelength

of light from distant galaxies.

24
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

25
Q

What does red-shift provide evidence for?

A

● Provides evidence that the universe is
expanding

● Supports the Big Bang theory

26
Q

What does the Big Bang theory suggest?

A

The entire universe started from a very

small, hot and dense region in space

27
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

28
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.

29
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

30
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