Calculating Speed

• Calculating Speed

  • For objects that are moving with a constant speed, use the equation below to calculate the speed:

  
• Where:

  • v = speed in metres per second (m/s)
  • s = distance travelled in metres (m)
  • t = time taken in seconds (s)
• Calculating Average Speed:

  • In some cases, the speed of a moving object is not constant
  • For example, the object might be moving faster or slower at certain moments in time (accelerating and decelerating)
  • Because its speed is not constant, it is moving with non-uniform motion
• • Total distance is again measured in metres, m
  • Total time is measured in seconds, s
  • Average speed is therefore also measured in metres per second, m/s
• • The equation for average speed can be rearranged with the help of a formula triangle as shown:

  
• Average Speed & Non-Uniform Motion:

  • The average speed of an object is rarely constant
  • Hikers change their pace continuously as they walk
  • Bumblebees buzz around in all directions with varying speed
  • Cars are constantly speeding up and slowing down throughout a journey
• • Non-uniform motion refers to motion that is changing
  • Changing motion can mean the object is changing its speed, direction or both
• Race drivers know all about non-uniform motion, especially slowing down for corners and speeding up on the straight sections of track: