P2- Topic 8 - Space

Question 1

Which galaxy is our solar system part of?

Answer 1

The Milky Way galaxy

Question 2

How many planets make up our solar system?

Answer 2

Eight (plus the dwarf planets).

Question 3

What do the planets in our solar system orbit around and what type of body is it?
2

Answer 3

planets orbit around the sun

sun is a star

Question 4

What type of force pulled together the

cloud of dust and gas to form the Sun?

Answer 4

Gravitational force of attraction

Question 5

What word is used to describe a cloud of dust and gas?

Answer 5

A nebula

mainly hydrogen

Question 6

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

Answer 6

Fusion reactions.

Question 7

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

Answer 7

Protostar phase

2. Main sequence phase

Question 8

Once a protostar is formed what does the lifecycle depend on

Answer 8

The size of the star

Question 9

how does nucleur fusion happen

Answer 9

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

Question 10

what happens when stars initially fom (nebulla) 1

Answer 10

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

Question 11

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

Answer 11

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

Question 12

what happens at the 3rd stage main sequence star 3

Answer 12

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

Question 13

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

Answer 13

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

Question 14

what happens to stars about the same size as the sun

Answer 14

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

Question 15

how does thee fusion processes lead to

the formation of new elements.

Answer 15

helium nuclei will undergo fusion to form beryllium

Question 16

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

Answer 16

a black dwarf

Question 17

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

Answer 17

neutron star

black hole

Question 18

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

Answer 18

red giant

white dwarf

Question 19

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?

Answer 19

red super giant

supernova

Question 20

What are produced during the fusion processes in a star?

Answer 20

All of the naturally occurring elements

Question 21

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

Answer 21

Very high temperatures

Question 22

How are elements heavier than iron produced?

Answer 22

In a supernova.

Question 23

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

Answer 23

Hydrogen nuclei fuse to form heavier

elements.

Question 24

How are elements distributed throughout the

universe?

Answer 24

Through the explosion of a massive star

supernova

Question 25

Why does the star begin to collapse inwards 2

Answer 25

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

Question 26

how do stars form heavier elements

Answer 26

helieium nuclei fuse together to form heavier element (beryllium) star than expands creating red giant

Question 27

what happens at the white dwarf (same sun) 3

Answer 27

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

Question 28

what happens at the black dwarf (same sun) 2

Answer 28

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

Question 29

what happens at the supernova (big sun) 2

Answer 29

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

Question 30

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

Answer 30

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

Question 31

What allows planets and satellites to maintain circular orbits?

Answer 31

● 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

Question 32

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

Answer 32

A natural satellite

Question 33

Give two examples of artificial satellites

Answer 33

1. TV satellites | 2. Satellites used for satellite imaging

Question 34

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) ```

Answer 34

● 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

Question 35

What is red-shift? 2

Answer 35

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

Question 36

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

Answer 36

● The further away a galaxy is, the faster it is moving ● The further away a galaxy is, the greater the observed increase in wavelength

Question 37

What does red-shift provide evidence for?2

Answer 37

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

Question 38

What does the Big Bang theory suggest?

Answer 38

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

Question 39

Compare the observed red-shift of two galaxies, one further away than the other

Answer 39

● The galaxy that is further away is travelling faster ● The observed red-shift is greater the further away it is

Question 40

Equation for red shift | Equation for red shift using recessional velocity

Answer 40

red shift = wavelength observed- wavelength emittied/ emitted red shift= recessional velocity/ speed of light (3*10⁸)

Question 41

What is blue shift and how is it proven 2

Answer 41

when the wavelength is 'squashed' and the wavelength is shortened if the recessional velocity is negative

Question 42

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

Answer 42

They observed supernovae, which suggested that galaxies are moving away at an ever faster rate

Question 43

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

Answer 43

● The rate of expansion was expected to occur at an ever slower rate ● It was thought that gravitational forces would cause this slowing down

Question 44

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

Answer 44

● 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