Topic 8 - Space Physics

Question 1

What are artificial satellites?

Answer 1

Man-made satellites that have been sent into space for purposes such as satellite imaging and communications.

Question 2

What is the big bang theory?

Answer 2

The currently accepted model for the origin of the universe. It suggests that the universe has expanded from an initially very small, hot and dense point.

Question 3

What is are circular orbits?

Answer 3

Planets and satellites travel in circular orbits. Gravity provides the required force for these orbits.

Question 4

What is dark energy?

Answer 4

A hypothesised form of energy, believed to be responsible for the
universe’s ever increasing rate of expansion.

Question 5

What is dark mass?

Answer 5

A hypothesised type of mass that cannot be observed by current methods. It is used to explain why some galaxies rotate faster than they should for their observed mass.

Question 6

What is a main sequence star?

Answer 6

The stable state of all stars. The gravitational forces
pulling the star together, and the pressure pushing outwards, are balanced.

Question 7

What is a milky way galaxy?

Answer 7

The galaxy in which our solar system is located.

Question 8

What is a natural satellite?

Answer 8

The moon that orbit planets.

Question 9

What is a nebula?

Answer 9

A cloud of dust and gas.

Question 10

What is a protostar?

Answer 10

The first stage all stars go through after forming from a nebula. In this stage the star becomes hot enough for hydrogen nuclei to fuse.

Question 11

What is a red giant star?

Answer 11

When their hydrogen is used up and larger nuclei are produced by fusion, stars of a similar magnitude to the Sun will expand to form a red giant.

Question 12

What is the red shift?

Answer 12

The observed increase in the wavelength of the light emitted by distant galaxies. The more distant the galaxy, the faster it is moving and so the bigger the observed increase in wavelength.

Question 13

What is the star life cycle?

Answer 13

The stages that a star passes through in its lifetime, dependent on the size of the star relative to the sun.

Question 14

What is the sun?

Answer 14

A star formed from a cloud of dust and gas being pulled together by gravitational attraction. Fusion reactions occur in the sun.

Question 15

What is a supernova?

Answer 15

The explosion of a massive star, that distributes the elements created by the fusion reactions in the star, throughout the universe.

Question 16

What is a white dwarf?

Answer 16

When the fusion reactions in stars of a similar magnitude to the sun come to an end, the star will contract under gravity and cool down to form a white dwarf.

Question 17

How many planets make up our solar system?

Answer 17

Eight (plus the dwarf planets)

Question 18

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

Answer 18

Gravitational force of attraction.

Question 19

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

Answer 19

Fusion reactions.

Question 20

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

Answer 20

• Protostar phase
• Main sequence phase

Question 21

What do stars of a similar magnitude to the sun become at the end of their life cycle?

Answer 21

A black dwarf.

Question 22

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

Answer 22

• Neutron Star
• Black Hole

Question 23

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

Answer 23

• Red Giant
• White Dwarf

Question 24

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 24

• Red super giant
• Supernova

Question 25

What are produced during the fusion processes in a star?

Answer 25

All of the naturally occurring elements.

Question 26

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

Answer 26

Very High Temperatures.

Question 27

How are elements heavier than iron produced?

Answer 27

In a supernova.

Question 28

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

Answer 28

Hydrogen nuclei fuse to form heavier elements.

Question 29

How are elements distributed throughout the universe?

Answer 29

Through the explosion of a massive star (supernova).

Question 30

What allows planets and satellites to maintain circular orbits?

Answer 30

- 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 it's circular orbit

Question 31

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

Answer 31

- 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 32

Explain how the force of gravity acting on a satellite affects it's speed and velocity.

Answer 32

- The force can alter it's 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 33

What does red- shift provide evidence for?

Answer 33

- Provides evidence that the universe is expanding - Supports the big bang theory

Question 34

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

Answer 34

- 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 35

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

Answer 35

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

Question 36

What two ideas could explain the universe's ever increasing grate of expansion?

Answer 36

- 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.