P16 Space Flashcards
Which nuclear reaction powers a star like our Sun and how does it work?
Fusion - light nuclei (hydrogen) are joined to produce heavier nuclei (helium) , releasing energy in the process due to the conversion of a small quantity of mass into energy
Which force is responsible for making mass attract mass, and is it a contact or a non-contact force?
Gravitational attraction, Non-contact force
What is a nebula?
A large cloud of gas and dust
When small nuclei fuse, what is always released?
Electromagnetic radiation
The birth and life of a star
- The fusion reaction becomes self-sustaining, which means it continues to happen by itself, and the star continues to shine because it is emitting electromagnetic radiation
- Eventually the radiation pressure outwards balances the gravitational force inwards
- The star is now a main sequence star and the star is in stable equilibrium. When the radiation pressure outwards and gravitational force inwards balance out, the star sustains its fusion reaction for billions of years
In what stage of a star’s life cycle does fusion occur?
Main sequence
The death of a low mass star
- When the star runs out of hydrogen nuclei to fuse together in its core, there is not enough to sustain equilibrium and it reaches the end of its main-sequence stage
- Its core collapses, and its outer layers swell down
- Stars about the same size as the Sun (or smaller), swell out, cool down and turn red
- These stars are now red giants
- The red giant then sheds some outer layers (which can go on to make new planets) and shrinks down to become a white dwarf, a planet sized, very hot body in the same location as the original star
What is an orbit?
The curved path taken by a moving body around another larger body, due to mutual gravitational attraction
What is the Earth in orbit around?
The Sun
What orbits the Earth?
The Moon
What is the difference between speed and velocity
- Speed is a scalar quantity, and only has magnitude
- Velocity is speed in a given direction, it is a vector quantity so has both magnitude and direction
Factors affecting orbits
- Direction of the velocity
- Direction of the gravitational force
What is the red-shift?
An observed increase in the wavelength of light from distant galaxies
How does the red-shift provide evidence for the Big Bang?
- Provides evidence that the universe is expanding
- Supports the Big Bang Theory
What is the Big Bang theory?
- All the matter in the universe was squashed into a tiny space
- The matter was thrown out very suddenly and very quickly, like an explosion
- All the energy in the universe formed matter
- The universe is getting bigger and bigger all the time. It is currently expanding
Why do stars in outer galaxies appear red?
- As the distance between the observer and outer galaxies increases, the wavelength of light emitted by these outer galaxies increases, whilst the frequency of the waves decrease
- Red light has a longer wavelength and lower frequency, so the wavelengths of light shift towards the red end of the EM spectrum
- The stars are moving away from us, so they appear to be red
Explain how this observation supports the Big Bang theory of the formation of the universe
- The furthest galaxies show the biggest red shift
- Meaning that the furthest galaxies are moving fastest
- So the universe is expanding
- The Universe started from an initial point (The Big Bang theory)
Explain why in circular motion (like orbits) the body is accelerating
- Acceleration is the change in velocity divided by time
- The resultant force due to gravitational attraction is always changing the direction of the orbiting body
- Since the direction is changing, the velocity is constantly changing
- The magnitude of the velocity remains constant but since the direction is changing, the velocity is changing
What is CMBR?
Cosmic microwave background radiation
What is the evidence to support the Big Bang theory?
CMBR and Red-shift
Explain why the star is stable while it is in the main sequence stage of its life cycle
The gravitational force inwards and forces as result of fusion reactions outwards are in equilibrium
Describe what will happen to a star, the same size and mass as the Sun, between the main sequence stage and the end of the star’s life cycle
- The star will expand to become a red giant
- The star will collapse to become a white dwarf
- The star will cool to become a black dwarf
What is in our solar system?
- One star, the Sun
- Eight planets
- Dwarf parents
- Natural satellites called moons that orbit planets
Explain how the sun and solar system was formed
- The universe contains clumps of dust and gas each called a nebula
- Gravitational attraction pulls this dust and gas together
- Forming the Sun
- Fusion reactions lead to an equilibrium between the gravitational collapse of the star and the expansion of a star due to fusion energy
- The remaining parts of the solar system form from the remaining dust and gas
What condition is required for fusion reactions to occur in a star?
Very high temperatures
What is a supernova?
The explosion of a star
Describe how stars are formed
Gravitational attraction pulls the dust and gas from space together, which forms stars
State why a star is stable during the ‘main sequence’ period of its life cycle
The expansion of main sequence star due to fusion is in equilibrium with the star collapsing due to gravity
Explain why, for circular obits, the force due to gravity can lead to an acceleration but an unchanged speed of the satellite
In circular orbits, the direction is constantly changing due to the force of gravity, therefore velocity is also always changing, so the satellite accelerates
Describe how the elements up to iron were created
- Nucelar fusion causes hydrogen nuclei to fuse creating helium nuclei
- As hydrogen runs out, the star begins to create heavier elements such as carbon, oxygen and iron
Why are telescopes that detect different types of electromagnetic waves used to observe the Universe?
Sources emit different types of electromagnetic waves radiation
What is red-shift? (1 mark)
Wavelength of light increases
Describe the ‘Big Bang’ theory
- All matter compressed to
- Cause a massive explosion which sends matter outwards
Suggest what scientists should do if new evidence were found that did not support the ‘big bang’ theory
Change the theory to match new evidence
What is meant by red shift and what does it tell us about distant galaxies?
- Longer wavelength waves
- Space is expanding
what are the stages in the life cycle of a star with a mass greater than the sun?
- nebula
- protostar
- main sequence star
- red supergiant
- supernova
- black hole or neutron star
what are the stages in the life cycle of a star with a mass about the same as the sun?
- nebula
- protostar
- main sequence star
- red giant
- white dwarf
- black dwarf
a main sequence star is in a stable state, explain why
the expansion of the main sequence star due to fusion is in equilibrium with the star collapsing due to gravity
explain why, for circular orbits, the force due to gravity can lead to an acceleration but an unchanged speed of the satellite
- in circular orbits, the direction is constantly changing
- due to the force of gravity
- therefore velocity is also always changing
- so the satellite accelerates
describe how the elements up to iron were created
- nuclear fusion causes hydrogen nuclei to fuse
- creating helium nuclei
- as hydrogen runs out, the star begins to create heavier elements
- such as carbon, oxygen and iron
describe how the sun was formed
- from a cloud of dust and gas, called nebula
- pulled together by gravitational attraction
- forming the sun
describe the relationship between the speed and the radius of an orbit
- if the speed of the object in orbit changes, the radius of the orbit also changes
- if the radius of the orbit decreases, the speed increases as the gravitational attraction is greater
- if the radius of the orbit increases, the speed decreases as the gravitational attraction is smaller
which objects orbit the sun?
dwarf planets, planets, comets and asteroids
how many planets are there in our solar system?
8
what orbits a planet?
moons
