Motion Graphs

Distance-Time Graphs

Remember to check what sort of graph it is!

  • The gradient (slope) of the graph will give us the speed, the steeper the gradient, the faster the object is moving.
  • A straight line always means CONSTANT speed; remember, a horizontal line means the object is stationary.
  • A curved line always shows a change in speed, (acceleration) - a steepening curve means it's getting faster, a flattening curve means it's getting slower.
  • A 'downhill' section means that it's heading back towards its starting point.

Velocity-Time Graphs

  • The gradient of the graph will tell us the acceleration of the object, the steeper the gradient, the greater the acceleration.
  • A negative acceleration will be indicated by a downwards slope.
  • A straight line will indicate CONSTANT acceleration and a horizontal line means CONSTANT velocity.
  • A curved line means changing velocity.
  • The area under the graph will tell us the distance travelled. Remember you can work this out by dividing the shape into triangle and rectangles.

You should know:

  • Velocity-time graphs of objects moving with a constant velocity are horizontal straight lines.
  • The gradient of a velocity-time graph gives the acceleration; a negative gradient indicates deceleration.
  • The distance travelled is equal to the area under a velocity-time graph.