Topic 7 🔭⭐️ Flashcards
Why does your weight vary across planets?
- Your weight is dependent on gravity.
- The gravitational field strength of a planet varies depending on size of the planet.
What is the gravitational field strength on Earth?
Approximately 10 N/kg
What does our solar system consist of?
- The sun (our star)
- 8 planets
- The planets natural satellites
- Dwarf planets
- Comets and asteroids
Name the planets in order.
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Describe the orbits of the moons, planets, comets and artificial satellites.
They orbit in an elliptical shape.
Describe the Steady State Theory.
The Steady State theory says that the universe has always existed but is expanding and creating matter to counteract the loss in density.
Describe the Big Bang theory.
The Big Bang theory states that the universe expanded from a very smaller dense point about 14 billion years ago ago.
What is red-shift?
A perceived increase in the wavelength of light due to the source moving away from the observer.
What does red-shift provide evidence for?
- The universe is expanding
- This supports the Big Bang theory
What does the Big Bang theory suggest?
The entire universe started from a very small, hot and dense region in space.
Compare the observed red-shift of two galaxies, one further away than the other.
- The galaxy that is further away is travelling faster.
- The observed red-shift is greater the further away it is
What did scientists observe to provide evidence that the universe is expanding at an ever faster rate?
They observed supernovae, which suggested that galaxies are moving away at an ever faster rate.
What does CMBR stand for?
Cosmic Microwave Background Radiation
What does CMBR provide further evidence for?
- The Big Bang Theory
- It it believed that CMBR originates from radiation produced in the Big Bang
How does the existence of CMBR support the expansion of the universe?
- It is thought that gamma radiation was released in the Big Bang
- The expansion of the universe has stretched this radiation, resulting in the microwave radiation present today.
What fact determines the type of lifecycle a star undergoes?
The size of the star
Which two phases do all the stars of the same or greater size than the sun undergo?
- Protostar phase
- Main sequence phase
What do stars like the sun become at the end of their life-cycle?
A black dwarf
What two things can stars much bigger than the universe become at the end of their lifecycle?
- Neutron star
- Black hole
What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?
- Red giant
- White dwarf
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?
- Red supergiant
- Supernova
Describe the transition of the star from the nebula stage to the main sequence.
- Nebula increases in size until it is pulled in due to its gravity, causing GPE to turn into KE.
- The collisions between particles cause this kinetic energy to turn into thermal energy.
- Eventually the nebula will become dense and hot enough to begin fusion.
What occurs in the stage when a star is a main sequence star?
- The fusion in the star releases energy
- This energy balances out with the gravitational potential energy leaving the star
- The star is in equilibrium so will not collapse due to gravity or expand due to radioactive behaviour. It is table
What environment is required for nuclear fusion to occur?
Higher temperature and high pressure
