Distance-Time & Speed-Time Graphs (CIE IGCSE Maths: Core)

How does a distance-time graph work?

• Distance-time graphs show distance from a fixed point at different times
  • Distance is on the vertical axis, and time is on the horizontal axis.
•  The gradient of the graph is the speed
  • 
• A positive gradient represents the object (or person) moving away from the starting point
• If the graph is a horizontal line the object is stationary (not moving)
• A negative gradient represents the object (or person) moving towards the starting point
• If the graph is a straight line the speed is constant
• If the graph is a curve you can draw the tangent at a point on the graph and find its gradient
  • This will be an estimate of the speed at that point

What is a speed-time graph?

• Speed-time graphs show speed at different times
  • Speed is on the vertical axis, and time is on the horizontal axis
• The gradient of the graph is the acceleration

  • 

• If the graph is a curve you can draw the tangent at a point on the graph and find its gradient
  • This will be an estimate of the acceleration at that point

• A positive gradient shows positive acceleration (speeding up)
• A horizontal line on a speed-time graph shows constant speed (no acceleration)
• A negative gradient shows negative acceleration, or deceleration (slowing down)

• The distance covered can be found by finding the area under the graph