Speed

• Distance

  How far an object moves, does not involve direction
• Displacement

  The distance an object moves in a straight line from the start point to the finish point, includes direction
• Distance

  A scalar quantity, has magnitude but no direction
• Displacement

  A vector quantity, has both magnitude and direction
• Speed


  The distance an object traveled divided by the time taken, a scalar quantity
• Calculating speed

  Distance traveled / Time taken
• The equation for speed is not given in the exam, so it must be learned
• Typical speeds

  • Normal walking speed: 1.5 m/s
  • Running speed: 3 m/s
  • Cycling speed: 6 m/s
  • Car on main road: 13 m/s
  • Fast train: 50 m/s
  • Cruising aeroplane: 250 m/s
  • Speed of sound in air: 330 m/s
• The speed of a moving object is rarely constant, but average speed is calculated over the total journey
• Calculating distance traveled at constant speed

  Distance (m) = Speed (m/s) x Time (s)
• The equation for calculating distance at constant speed is not given in the exam, so it must be learned