P1 REVISION!!

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  • P1-The Earth and the Universe
    • Beyond Solar System
      • Milky way galaxy, sun is in middle of one of the spiral arms of the galaxy
      • Every galaxy is made up of thousands of millions of stars
      • The Universe has more than a thousand million galaxies
      • Distance in space is measured in light years
      • Age of stuff in space
        • Earth: 5000 million years
        • Sun: 5000 million years
        • Universe: 14000 million years
    • Looking in Space
      • Stars
        • Emit electromagnetic radiation
        • Measuring distance 'how far away they are'
          • Parallax
          • Brightness emitted (not as reliable)
      • problems to see things in space
        • Earth's atmosphere
        • Light Pollution
      • Stars are never seen in the present, e.g. the sun radiation reaches us in 8 minutes so whatever happens to the sun now will happen to us in 8 minutes
    • Life of the Universe
      • It's expanding
        • Red Shift . further = redder light = faster
        • Big Bang Theory. There must be a force pushing the universe away from it's core. (stretching it)
      • Will it end one day?
        • Ultmate fate relies on how fast it's expanding and the total mass in it
          • Not always accurate results.
          • Hard to measure
          • More mass = greater gravitational pull = slower expansion of universe - ending with a big crunch
          • Less mass = eternal expansion of universe
    • Changing Earth
      • The Earth is always changing, in a few million years the Earth map will be very different as the continents would have all moved
      • Proof that Eearth has been changing and will continue.
        • e.g. Colorado River has eroded the rock of the Grand Canyon leaving a woven valley shape through Arizona
        • Cliffs are worn off by seas. We can see this ourselves
        • Lava from volcanic eruptions forms new rock when it cools.
        • Fossils show that new rock is always forming.
          • Lava from volcanic eruptions forms new rock when it cools.
        • Layer of Rock , older = lower layer
        • Rock Cycle
          • Particles eroded = sedimentary
            • Heat, pressure from core change crystal allignment = metamorphic
          • Melted, cools slow or quick = igneous rock
            • Instrusive (inside)
            • Extrusive (outside)
          • Some rocks can be folded
    • Continental Drift - Wegener's theory
      • His Evidence for theory
        • Coastlines of Africa and South America seemed to fit together
        • Glacier scratches in modern day 'hot' countries with forests
        • Fossils of similar animals found on different sides of Earth
      • Why Rejected
        • He wasn't even a geologist
        • He didn't know how the continents could have moved.
      • Why accepted
        • When: During World War 2
        • Sea Floor Spreading
          • Iron, magnetic stripes were detected on the ocean bed.
            • Every half million years the Earth's magnetic field swaps so there are zig zag shaped stripes
      • Pangaea -Supercontinent
    • The Earth's structure
      • Crust
        • Continental - forms land
        • Oceanic - under oceans
      • Mantle
        • Has all properties of solid but can flow slowly. Made up of Molten Rock
      • Core
        • This heats the mantle and causes the magma to flow in convection currents.
        • Thought to be made up of mainly iron and nickel.
      • Tectonic Plates - USE YOUR GEOGRAPHY
    • Seismic Waves
      • Earthquakes produce wave motions (shock waves) that travel on the surface and inside the Earth.
      • Measured using SEISMOGRAPHS by SEISMOLOGISTS, who measure how long the waves take to travel
      • P Waves
        • Travel through solids and liquids
        • Longtitudinal
        • Have a sudden change in properties as u go from the mantle to core.
        • Seem to travel faster through middle of core suggesting that inner core= solid.
      • When the waves reach a boundary between different layers of Erth some will be reflected.
      • When properties (e.g. density) of the mantle or core change the waves change speed and direction, which is refraction.
        • If they change too quickly, it can result in a curved path
    • Waves
      • They all have:
        • Amplitude (distance from the rest position to the crest or trough
        • Wavelength (length of the full cycle of the wave)
          • When the speed is constant, the wavelength is inversely proportianal  to the frequency.
            • Frequency (the number of complete waves passing a certain point per second OR the number of waves produced by a source per second
          • Waves with lower frequencies have longer wavelengths and those with higher frequencies have lower wavelengths.
            • Frequency (the number of complete waves passing a certain point per second OR the number of waves produced by a source per second
        • Speed (SPEED)
          • When the speed is constant, the wavelength is inversely proportianal  to the frequency.
        • Transverse
          • e.g. light, other EM waves, S waves
          • The vibrations are at 90 degrees to the wave's direction of travel
        • Longitudinal
          • e.g. sound, ultrasound, P waves
          • The vibrations are at the same direction.
        • Wave speed (m/s) = Frequency (Hz) x Wavelength (m)
        • distance (m) = speed (m/s) x time (s)
        • Carry and transfer energy in the wave travel direction, DON'T TRANSFER MATTER
        • Disturbances caused by a vibrating source.
      • The Solar System
        • There are 8 planets orbiting the sun in elipses (circular paths)
          • Closest to Sun:Mercury, Venus, Earth and Mars
          • Furthest from Sun: Jupiter, Saturn, Uranus and Neptune
          • Asteroid belt in middle of inner and outer planets
        • Moons orbit planets
        • Planets only reflect light whereas stars give out lights so you can see them even though they are very far away
        • Formation
          • Big clouds of dust and gas collapsed in on themselves due to gravity
            • Fusion took place when the temperature got high and particles joined to form a protostar
              • Fusion: Hydrogen nuclei joined together to make helium
              • Fusion gives out lots of heat and light thus a star, the sun, was born
                • Fusion: Hydrogen nuclei joined together to make helium
          • Around the sun, material from cloud containing hydrogen, helium etc. started to clump together, forming planets
          • Left over material = asteroids and comets
            • Comets = rock, dust and ice. Orbit sun in elongated elipses
            • Asteroids = rubble of rock between Mars and Jupiter

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