P8 (pmt)

Question 1

What is red-shift?

Answer 1

An observed increase in the wavelength

of light from distant galaxies

Question 2

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

Answer 2

● 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 3

What does red-shift provide evidence for?

Answer 3

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

Question 4

What does the Big Bang theory suggest?

Answer 4

The entire universe started from a very

small, hot and dense region in space.

Question 5

Compare the observed red-shift of two galaxies, one

further away than the other

Answer 5

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

Question 6

What did scientists observe to provide evidence that

the universe is expanding at an ever faster rate?

Answer 6

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

Question 7

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

Answer 7

● 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 8

What two ideas could explain the universe’s ever

increasing rate of expansion?

Answer 8

● 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

Question 9

Which galaxy is our solar system part of?

Answer 9

The Milky Way galaxy.

Question 9

Which galaxy is our solar system part of?

Question 10

How many planets make up our solar system?

Answer 10

Eight (plus the dwarf planets).

Question 11

What do the planets in our solar system orbit around

and what type of body is it?

Answer 11

● The planets orbit around the sun

● The sun is a star

Question 12

What type of force pulled together the cloud of dust
and gas to form the Sun?
]

Answer 12

Gravitational force of attraction.

Question 13

What word is used to describe a cloud of dust and

gas?

Answer 13

a nebula

Question 14

What type of reactions take place at the start of a

star’s life cycle as dust and gas is drawn together?

Answer 14

Fusion reactions.

Question 15

What factor determines the type of lifecycle a star

undergoes?

Answer 15

The size of the star

Question 16

Which two phases do all stars of the same or greater

size than the sun undergo?

Answer 16

1. Protostar phase

2. Main sequence phase

Question 17

What do stars of a similar magnitude to the sun

become at the end of their life-cycle?

Answer 17

A black dwarf.

Question 18

What two things can stars much bigger than the sun

become at the end of their lifecycle?

Answer 18

1. Neutron star

2. Black hole

Question 19

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

Answer 19

1. Red giant

2. White dwarf

Question 20

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 20

1. Red super giant

2. Supernova

Question 21

What are produced during the fusion processes in a

star?

Answer 21

All of the naturally occurring elements

Question 22

What condition is required for fusion reactions to

occur in a star?

Answer 22

Very high temperatures

Question 23

How are elements heavier than iron produced?

Answer 23

In a supernova.

Question 24

What type of nuclei fuse together to form heavier

elements in a star?

Answer 24

Hydrogen nuclei fuse to form heavier

elements.

Question 25

How are elements distributed throughout the

universe?

Answer 25

Through the explosion of a massive star

supernova

Question 26

What allows planets and satellites to maintain

circular orbits?

Answer 26

● 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 27

What type of satellite can a planet’s moon be

described as?

Answer 27

A natural satellite

Question 28

ve two examples of artificial satellites

Answer 28

1. TV satellites

2. Satellites used for satellite imaging

Question 29

Explain why for a stable orbit, the radius of orbit

must change if the speed changes

Answer 29

● 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 30

Explain how the force of gravity acting on a satellite

affects its speed and velocity

Answer 30

● 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

Question 31

White Dwarf: