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Physics > P2- Topic 8 - Space > Flashcards

P2- Topic 8 - Space Flashcards

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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?
2

A

planets orbit around the sun

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

mainly hydrogen

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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

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

A

Protostar phase

2. Main sequence phase

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8
Q

Once a protostar is formed what does the lifecycle depend on

A

The size of the star

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9
Q

how does nucleur fusion happen

A

Stars get denser, temperature rises and more partical collisions happen

temperature gets high enough, hydrogen nuclei undergo nuclear fusion to form helium nuclei

gives huge amount of energy, core of star is hot a star is born

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10
Q

what happens when stars initially fom (nebulla) 1

A

All stars form from a giant cloud of hydrogen gas and dust called a nebula

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11
Q

what happens at the second stage of a star forming (protostar)
3

A

force of gravity within a nebula pulls the particles closer together until it forms a hot ball of gas (protostar)

particles pulled closer together the density of the protostar increases

more frequent collisions between the particles which causes the temperature to increase

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12
Q

what happens at the 3rd stage main sequence star 3

A

Once the protostar becomes hot enough, nuclear fusion reactions occur within its core

hydrogen nuclei will fuse to form helium nuclei

Every fusion reaction releases heat (and light) energy which keeps the core hot

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13
Q

why at the main sequence star the star is said to be stable 2

A

During the main sequence, the star is in equilibrium and said to be stable

inward force due to gravity is equal to the outward pressure force from the fusion reactions

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14
Q

what happens to stars about the same size as the sun

A

Run out of hydrogen to fuse. Core collapses and outer layers swell which causes it to cool​

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15
Q

how does thee fusion processes lead to

the formation of new elements.

A

helium nuclei will undergo fusion to form beryllium

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16
Q

What do stars about the same size of
the sun become at the end of their
life-cycle?

A

a black dwarf

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17
Q

What do stars much bigger than the sun become at the end of their life-cycle? 2

A

neutron star

black hole

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18
Q

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

A

red giant

white dwarf

19
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

20
Q

What are produced during the fusion processes in a star?

A

All of the naturally occurring elements

21
Q

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

A

Very high temperatures

22
Q

How are elements heavier than iron produced?

A

In a supernova.

23
Q

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

A

Hydrogen nuclei fuse to form heavier

elements.

24
Q

How are elements distributed throughout the

universe?

A

Through the explosion of a massive star

supernova

25
Q

Why does the star begin to collapse inwards 2

A

the inward force due to gravity will become greater than the outward force due to the pressure of the expanding gases

as the fusion dies down

26
Q

how do stars form heavier elements

A

helieium nuclei fuse together to form heavier element (beryllium)

star than expands creating red giant

27
Q

what happens at the white dwarf (same sun) 3

A

The core which is left behind will collapse completely

due to the pull of gravity, and the star will become a white dwarf

The white dwarf will be cooling down and as a result, the amount of energy it emits will decrease

28
Q

what happens at the black dwarf (same sun) 2

A

Once the star has lost a significant amount of energy it becomes a black dwarf

It will continue to cool until it eventually disappears from sight

29
Q

what happens at the supernova (big sun) 2

A

core of the star will collapse suddenly causing a gigantic explosion when fusion reactions stop

At the centre of this explosion a dense body, called a neutron star will form

30
Q

what happens at the neutron or(black hole) - bigsun

A

neutron star will continue to collapse under the force of gravity until it forms a black hole

black hole is an extremely dense point in space that not even light can escape from

31
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

32
Q

What type of satellite can a planet’s

moon be described as?

A

A natural satellite

33
Q

Give two examples of artificial satellites

A
  1. TV satellites

2. Satellites used for satellite imaging

34
Q

Explain why for a stable orbit, the radius of orbit must change if the speed changes 3

use equation F=mv²/r
F=centripetal force (N)
m= mass (kg)
velocity= (m/s)
r= radius of circular motion (m)
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

35
Q

What is red-shift? 2

A

An observed increase in the wavelength
of light from distant galaxies meaning it is moving towards the red end of the spectrum (microwaves and infared)

This is as the universe is expanding

36
Q

What two things can be said about the motion and wavelength of emitted light from a galaxy, the further
away it is? 2

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

37
Q

What does red-shift provide evidence for?2

A

● Provides evidence that the universe is
expanding
● Supports the Big Bang theory

38
Q

What does the Big Bang theory suggest?

A

The entire universe started from a very

small, hot and dense region in space.

39
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

40
Q

Equation for red shift

Equation for red shift using recessional velocity

A

red shift = wavelength observed- wavelength emittied/ emitted

red shift= recessional velocity/ speed of light (3*10⁸)

41
Q

What is blue shift and how is it proven 2

A

when the wavelength is ‘squashed’ and the wavelength is shortened

if the recessional velocity is negative

42
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

43
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

44
Q

What two ideas could explain the
universe’s ever increasing rate of
expansion? 2

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

Physics (10 decks)

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