5) Astrophysics Flashcards
What is the universe?
- a large collection of billions of galaxies
What is a galaxy?
- a large collection of billions of stars
What is the name of our solar system?
- milky way
What does the gravitational field strength of a planet depend on?
- radius of planet
- density of planet
What is the relationship between mass and gravitational force?
gravitational force is directly proportional to the mass
What is the relationship between gravitational force and distance?
gravitational force is inversely proportional to the distance
As the distance increases, the gravitational force ___________
- decreases
As the mass increases, the gravitational force ___________
- increases
What is the equation to find orbital speed (v)?
v = 2πr/T v = orbital speed (km/s) r = orbital radius (km) T = time period (seconds)
Why does gravity cause things to orbit things (in general)
- gravity pulls things to the ground
- gravity acts on all stars, planets, moons
When is GPE strongest?
- furthest away
What is a comet?
- ball of dust and ice that travels through the solar system
What type of orbits do comets have?
- elongated elliptical orbits
Why do comets have 2 tails?
- gas tail - points directly away from the Sun due to ‘solar winds’ (electrically charged particles streaming out of the Sun) that push it back
- dust tail - lags behind the gas tail
Describe the orbit of a comet referring to its GPE and KE:
- KE is fastest when close to the Sun
- GPE is lowest when close to the Sun
- KE of comet decreases as gravitational pull decreases when comet is moving away from Sun
- GPE increases as comet moves away from Sun
- KE lowest when furthest from Sun
- GPE highest when furthest from Sun
- GPE decreases as comet moves towards Sun
- KE increases as comet moves towards Sun as gravitational pull increases
How are stars classified?
- according to their colour
What is the order of star classification from highest temperature to lowest temperature? What is each of these classes temperature? What is each of these classes colour?
O - more than 33,000 K - blue B - 10,000 - 33,000 K - blue white A - 7,500 - 10,000 K - white F - 6,000 - 7,500 K - yellow white G - 5,200 - 6,000 K - yellow K - 3,700 - 5,200 K - orange M - 2,000 - 3,700 K - red
What is the life cycle of a star that has a similar mass to the Sun?
- stellar nebula
- main sequence star
- red giant
- white dwarf
- black dwarf
What is the life cycle of a star that has a greater mass than the Sun?
- stellar nebula
- main sequence
- red super giant
- supernova
- neutron star
- black hole
What is a stellar nebula?
- cloud of cold hydrogen gas and dust which is collapsing due to the pull of gravity
What is main sequence star?
- the star releases energy from the fusion of hydrogen to form helium
- the forces are balanced
How does a main sequence star become a red giant?
- due to hydrogen shortage, the main sequence star becomes unstable
- the outward forces decrease and the star begins to collapse
- this brings additional hydrogen into a zone where the temperature and pressure are sufficient to cause fusion
- the outer layers expand greatly and the star enters the red giant phase
How does a red giant become a white dwarf?
- helium starts to fuse to make heavier elements such as carbon and oxygen
- eventually the star is no longer able to fuse helium and its core cools down
- the star collapses into a white dwarf
How does a white dwarf become a black dwarf?
- the white dwarf starts to cool down and it will eventually become a dark cold star
