Motion

• Distance


  The distance between two points is how far they are apart
• Displacement

  Measures their distance apart and specifies the direction
• Speed

  The rate at which distance travelled changes with time
• Velocity

  The rate of change of displacement with time
• Average speed


  Total distance travelled divided by total time taken
• Average velocity


  Total displacement divided by total time taken
• Jo walks around the three sides of the sports pitch

  1. Time taken: 250 seconds

  2. Distance travelled: 400 metres

  3. Final displacement: 200m to the right of starting position
• Jo's average speed is 1.6m/s
• Rate of change of speed

  Final speed - initial speed divided by time taken
• Rate of change of speed has no direction since speed has no direction
• If the rate of change of speed is constant, then average speed can be calculated from the formula: average speed = (initial speed + final speed) / 2
• If the starting position and finishing position are the same, then the total displacement will be zero and hence the average velocity must be zero