Distance-Time Graphs

A distance-time graph shows how the distance of an object moving in a straight line (from a starting position) varies over time:

Constant Speed on a Distance-Time Graph

• Distance-time graphs also show the following information:

  • If the object is moving at a constant speed

  • How large or small the speed is

  
  

• A straight line represents constant speed

• The slope of the straight line represents the magnitude of the speed:

  • A very steep slope means the object is moving at a large speed

  • A shallow slope means the object is moving at a small speed

  • A flat, horizontal line means the object is stationary (not moving)

Changing Speed on a Distance-Time Graph

• Objects might be moving at a changing speed

  • This is represented by a curve

  
  

• In this case, the slope of the line will be changing

  • If the slope is increasing, the speed is increasing (accelerating)

  • If the slope is decreasing, the speed is decreasing (decelerating)

  
  

• The image below shows two different objects moving with changing speeds

Changing speeds are represented by changing slopes. The red line represents an object slowing down and the green line represents an object speed