space physics Flashcards
(18 cards)
why is the sun stable
because gravitational forces acting inwards balance the forces of nuclear fusion energy in the core acting outwards
what is a protostar
concentration of gas and dust that becomes hot enoygh to cause nuclear fusion
life cycle of a star smaller/similar size to the sun
-nebula
-gravity causes fusion recations, turns into protostar
-protostar turns into main sequence star through fusing hydrogen nuclei into helium nuclei
-the main sequence star will carry on undergoing fusion reactions until the hydrogen runs out
-main sequence star will turn into red giant, during this tie heavy elements are formed n the core
-red giant become unstable and fusion stops, hydrogen begins to run out, outer layer of gas will shed
-star gets smaller and smaller exposing the core as a white dwarf
- the white dwarf cools to form black dwarf
life cycle of a star bigger than the sun
-nebula
-gravity causes fusion reactions, turning the nebula into a protostar
-protostar will turn into main sequence star, through fusing hydrogen nuclei into helium nuclei
-main sequence star will carry on with fusion recations until the hydrogen runs out in the core
-main sequence star will turn into red super gaint, undergoing more fusion reactions in its core. During this time, elements heavier than iron are formed in the core, causing outer layer of star to shed
-red super giant explodes into a supernova
-once the star has exploded, the leftover core will be called a nuetron star
-stars high in mass will form a black hole
red shift
light waves are stretched out if a star or galaxy is moving away from you
blue shift
light waves are squashed together if the star or galaxy is moving towards you
the faster the galaxy is moving
the bigger the shift is
evidence for the big bang
cosmic microwave background radiation (CMBR)- radiation coming from all directions in space
what provides the centripetal force
gravity
what factors determine the size of centripetal force on the satellite
-speed/velocity of the satellite
-mass of the satellite
-radius of orbit
explain how the different elements now contained in the universe were formed
-by nuclear fusion
-of hydrogen to helium
-elements heavier than iron are formed in a supernova
geostationary satellite
-goes along equator
-takes 24 hours to complete orbit
-Used for radio and telecommunication broadcasting around the world due to its high orbit
-At a height of 36 000 km above the Earth’s surface, much higher than polar satellites
polar satellites
Polar, or low orbit, satellites orbit around the Earth’s north and south poles
These orbit much lower than geostationary satellites, at around 200 km above sea level
Used for monitoring the weather, military applications, and taking images of the Earth’s surface
There is a much shorter time delay for signals compared to geostationary orbit signals
The signals and images are much clearer due to the lower orbit
However, there is limited use in any one orbit because more than one satellite is required for continuous operation
orbital radius
separation distance between the object in orbit and the centre of the object it is orbiting
If the speed of the satellite is too slow:
The radius of the orbit will decrease and the satellite will be pulled towards the object it should be orbiting
This is because the gravitational attraction is too strong to maintain a constant orbital radius
To maintain a stable orbit
If the speed increases the radius must decrease
If the speed decreases the radius must increase
doppler effect
A stationary observer in front of a moving source the frequency of the wave increases. When the stationary observer is behind the moving source then the frequency of the wave decreases
black body radiation
electromagnetic radiation emitted by an object due to its temperature.
