Space

Question 1

what are the two theories for the creation of the world?

Answer 1

steady state theory
big bang theory

Question 2

what is the steady state theory?

Answer 2

the universe was not created, it always existed

Question 3

what is the big bang theory?

Answer 3

the universe was created from a single point by a very big explosion

Question 4

what evidence are there for the universe expanding?

Answer 4

the red shift
CMBR (cosmic microwave backcground radiation)

Question 5

define the red shift

Answer 5

the change in wavelength of the light obtained from increasing distant galaxies

Question 6

define cosmic background radiation

Answer 6

any radiation from space that is always present

Question 7

the red shift

Answer 7

• when wavelengths shift towards the red end of the spectrum.
• red has the highest frequency therefore as the wavelength increases the frequency also increases.

Question 8

observations of the red shift

Answer 8

the red shift accelerates due to the decrease in gravity as it moves further away.
- the greater the red shift, the greater the speed of the galaxy.
- the greater the red shift, the further the galaxy.
- using the red shift, the distance and speed can be calculated.

Question 9

cosmic microwave background radiation

Answer 9

• only gamma + x-rays are emitted from the star by nuclear fusion
• as wavelength increases, the frequency also increases
• therefore, gamma + x-ray becomes UV - VL - IR… etc

currently, our universe is full of microwave radiation.

Question 10

up to red giant/super red giant

Life cycle of stars

(6 marker)

Answer 10

• the stardust and gas is pulled together by gravity to form clusters.
• this forms a nebula
• due to the gravitational force, the frequency of collisions between hydrogen nuclei increases, increasing the temperature.
  -this forms a protostar
• the higher temperature initiates nuclear fusion between hydrogen nuclei to form helium nuclei
• this emits outwards radiation pressure as well as inward gravity.
• once the inwards gravitational force + outwards radiation pressure balance eachother the star becomes a balanced object.
• this forms a small/big main sequence star.
• the star remains stable for a long period of time +continuously goes through nuclear fusion.
• eventually, the hydrogen nuclei run out which decreases the rate of nuclear fusion, decreasing the amount of radiation pressure.
• this causes the star to swell and emits infrared radiation.
• this forms a red giant/super red giant.
  -only helium nuclei is left as hydrogen nuclei runs out; helium nuclei begins to fuse.
• ## this forms heavier elements up to iron

Question 11

Red giant

Rest of the life cycle

(6 marker)

Answer 11

• the red giant begings to lose energy.
• so it becomes a white dwar and only emits visible light.
• eventually, nuclear fusion stops and a black dwarf forms.

Question 12

Super red giant

Rest of the cycle

(6 marker)

Answer 12

• a part of the super red giant explodes.
• this becomes a supernova.
• elements heavier than iron are fofrmed in the supernova.
• supernovas also scatter stardust into space.
• the cycle continues and stardust forms into a nebula again.

Unexploded parts
- either becomes a neutrino star + gets lost into space.
- or it becomes a blackhole.

Question 13

what can be used to identify the elements formed?

Answer 13

flame emission spectroscopy

Question 14

why is high amounts of energy required for nuclear fusion?

Answer 14

the nuclei repel eachother since they both have a positive charge.

Question 15

what are stars made of?

Answer 15

stardust and gas (hydrogen nuclei)

Question 16

how does a protostar form?

(2 marker)

Answer 16

• the increased collisions between hydrogen nuclei increase the temperature.
• the increase in temperature forms a protostar.

Question 17

how is a nebula formed?

(2 marker)

Answer 17

• stardust and gas are pulled together by gravity.
• they start to form clusters called nebulas.

Question 18

what can a red giant become?

(2 marker)

Answer 18

• a white dwarf (only emits visible light)
• a black dwarf

Question 19

how is a red/super red giant formed?

(3 marker)

Answer 19

• hydrogen nuclei run out, decreasing rate of nuclear fusion.
• this decreases amount of radiation pressure.
• the star begins to swell and emits infrared radiation.

Question 20

what can a super red giant become?

(3 marker)

Answer 20

• a supernova
• a blackhole
• a neutrino star

Question 21

how is a supernova formed?

Answer 21

• a part of the supr red giant explodes.

Question 22

how is a main sequence star formed?

Answer 22

• the inwards gravitational force + the outwards radiation pressure balance eachother.
• so the star becomes a balanced object, forming a main sequence star.