motion

• Distance


  Numerical description of how far apart two things are
• Scalar


  A quantity that requires only a size, for example, distance travelled is 20 m
• Speed


  The distance travelled in a known time period, eg miles per hour or kilometres per hour
• Rate of change


  The amount of change in the size of a quantity each second
• Typical speeds


  • Walking: 1.5 m/s
  • Running: 3 m/s
  • Cycling: 6 m/s
  • Car: 13-30 m/s
  • Train: 50 m/s
  • Aeroplane: 250 m/s
• The speed of the wind and the speed of sound also vary
• A typical value for the speed of sound in air is about 330 m/s
• A light breeze moves at perhaps 3 m/s, but a gale would be more than 20 m/s
• Calculating speed


  Speed = distance travelled / time taken
• Calculating distance


  Distance = average speed x time taken
• Equipment for measuring speed

  • Ruler and stopwatch
  • Light gates
  • Video analysis
• To calculate the speed of an object two measurements are needed: how far it travels and the time it takes to move that distance