Physics

• Displacement


  Distance in m
• Wave properties


  • Seismic waves are caused by earthquakes, and can be transverse or longitudinal
  • A long spring can model both types of wave
  • Sound waves are longitudinal
  • Pressure differences in a sound wave can appear transverse
• Transverse wave


  Wave where the wave oscillates at right angles to the direction of travel
• Snapshot


  A photograph of a wave showing a single point in time
• Wavelength


  The distance between one point on a wave to the same point on the next wave
• Time trace


  A graph showing what each coil of a spring is doing as time passes
• Period


  The time for one wave
• Amplitude


  The maximum displacement of a wave
• Longitudinal wave


  A wave where the wave oscillates in the same direction as the direction of travel
• Seismic waves


  Waves caused by earthquakes
• 1. wave


  Primary, or pressure wave. Longitudinal and similar to sound waves
• 1. wave


  Secondary wave. Transverse
• Seismic waves have the same properties as other waves like light and sound. They have a wavelength, an amplitude, a frequency, and a period
• The frequency, or the number of waves per second, is very low for seismic waves. P-waves and S-waves have frequencies of between 1Hz and 100Hz
• If a wave has a frequency of 1 Hz


  There will be one wave per second, so the period (time for one wave) will be 1 s
• If a wave has a frequency of 2 Hz

  There will be two waves per second, so the period will be 0.5 s
• Making a transverse wave on a spring


  Move your hand at right angles (90°) to the spring
• Making a longitudinal wave on a spring

  Move your hand in the same direction as the spring
• Student making waves on a Slinky


  • Transverse wave
  • Frequency of 2 Hz
• Transverse wave on oscilloscope


  Even though sound waves are longitudinal
• The SI unit of energy is the joule (J).
• Work done = force x distance moved in direction of force
• Energy can be transferred from one object to another by work done or heat transfer.