P1 Summary

  • Created by: icanteven
  • Created on: 02-01-15 13:01
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  • P1 Summary
    • Scientific Explanations
      • Scientists use journals and conferences to inform about their experiments and explanations.
      • A scientists' judgement about an explanation may be affected by their personal background.
      • An explanation is only accepted when it can account for all the data.
      • Scientists repeat experiments done by others to check their data.
    • The Solar System
      • The solar system was formed from gas and dust in space about 5000 million years ago.
      • The distance from a star can be estimated from its brightness and parallax.
      • The source of the Suns energy is fusion of hydrogen nuclei, making it hot enough to emit light, which moves through space at 300 000 km/s
      • The star at the centre of the solar system is called the sun.
      • Earth is one of eight planets which orbit around the sun.
      • Comets, asteroids and dwarf planets orbit the sun.
    • Galaxies
      • The sun is one of thousands of millions of stars in the Milky Way Galaxy.
      • The universe is made up of thousands of millions of galaxies.
      • Redshift and distance data suggest that the Universe expanded from a single point about 14 000 million years ago.
      • The redshift of light from galaxies can be used to measure how fast they appear to be moving away.
      • The expansion of space means that the greater the distance to a galaxy, the faster it appears to be moving away.
    • The Changing Earth
      • The oldest rocks on Earth are about 4000 million years old.
      • Mountain building, earthquakes, seafloor spreading and volcanoes happen at the edges of tectonic plates.
      • The Earth's solid crust floats on a soft mantle and is continually worn down by erosion.
      • Convection currents in the mantle split the crust into tectonic plates and move them.
      • The theory of tectonic plates explains Wegner's idea of continental drift.
    • Seismic Waves
      • Distance moved by a wave = wave speed x time of travel
      • Wave Speed = frequency x wave length
      • Waves have an amplitude, wavelength, frequency and speed.
      • Earthquakes produce waves which carry enough energy as they travel through the Earth.
        • P-waves are longitudinal waves which can move through the liquid core.
        • S-waves are transverse waves which can only move through the solid mantle and crust.


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