Universe, OCR- Unit 5, module 5

Universe, OCR- Unit 5, module 5

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  • Created on: 13-05-12 18:40
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Physics Unit 5, module 3
Sameer Jahabarali Physics
The structure of the universe compromises of the following components:
Galaxies- compromises of billions of clusters of stars rotating slowly towards their own
centre of gravity
Stars- `powerhouses' that emit energy in the form of electromagnetic radiation from nuclear
fusion that takes place within
Planets- are relatively cold objects that orbit stars
Planetary satellites- objects that orbit planets
The solar system is a region within the galaxy, where a central star and its gravitational force cause
the orbit of:
Planetary satellites
Comets- ice and rock together with a cloud of gas,
originated from Kuiper Belt
Asteroids- rock that orbit the sun, (meteor are
asteroid that enter the earths atmosphere)
Stars are formed by interstellar dust and gas, where:
Nebulae forms in regions where density of gas and
cosmic dust in space become high, where temperatures will rise
high enough to glow (release light energy)
A pro star (material core) forms as atoms collapse on its
own gravity- density and internal energy continue to increase
It becomes bigger and hotter, until the surface is hot
enough to emit light
The core temperature and pressure is high enough for
nuclear fusion (hydrogen fuse to helium)
A star is formed
Fate of the sun:
The sun's core will run out of hydrogen, so nuclear fusion can't take place within the core
This causes the core to contract, increasing temperature and pressure
This will cause the sun grow to a red giant
Helium fusion takes place in hot and dense core
Once helium runs out, the sun becomes unstable
It will than collapse on its self to a white dwarf, will become very dense
The remnant will gradually cool and form a dense matter
Fate of the massive stars differs when it:
Forms a super red giant

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Physics Unit 5, module 3
Sameer Jahabarali Physics
Which will collapse on its self to form a :
o Neutron star- star that fuses electrons and protons to form a neutron that will collapse
and explode to form a supernova (intense amount of energy, where elements on the
periodic table are formed and originates from).…read more

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Physics Unit 5, module 3
Sameer Jahabarali Physics
the direction of the particle motion and longer in the opposite direction.
Hubble's Redshift is the astronomical version of the Doppler
Effect. Hydrogen spectrum of distant stars in the Milky Way shifts
slightly more to the `red end'. When Hubble looked at data for
some galaxies, the data obtained matched the pattern but was
shifted marginally towards the `red end'.…read more

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Physics Unit 5, module 3
Sameer Jahabarali Physics
The standard model (hot big bang) of the universe implies a finite age for the universe. The age of the
universe is given by age of universe: 1/H0.…read more

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Physics Unit 5, module 3
Sameer Jahabarali Physics
Critical density is the minimum mean density of the universe, for the
galaxies to have greater kinetic energy than gravitational potential energy.
This is so the universe doesn't collapse on its self (the big crunch). It is
currently believed that the density of the universe is close to, and possibly
exactly equal to, the critical density needed for a `flat' cosmology.…read more


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