Distance, Displacement, Speed & Velocity

• Speed


  A scalar quantity that only has magnitude (size or extent)
• Velocity


  A vector quantity that has both magnitude and direction
• Distance


  A scalar quantity that only has magnitude
• Displacement


  A vector quantity that has both magnitude and direction
• Calculating speed


  Distance / Time
• Calculating velocity


  Displacement / Time
• The benefit of using velocity is that you can have a negative velocity to represent going backwards
• Objects often don't move at a constant speed but vary along their journey
• Example speeds in m/s

  • Walking: 1.5
  • Running: 3
  • Cycling: 6
  • Car on main road: 25
  • Fast train: 55
  • Plane: >250
• Sound waves travel at 330 m/s in air
• Wind speed can vary from almost 0 m/s to faster than a speeding train, affected by temperature, atmospheric pressure, and structures