Distance-Time Graph

Key Stage 3

Meaning

A distance time graph is a graph that shows how the distance of an object from the origin changes with time.

About Distance Time Graphs

Distance-time graphs give information about the journey taken by an object.

On a distance time graph the distance is plotted on the y-axis and the time is plotted on the x-axis.

A distance time graph can show the speed of an object.

Slow Speed	Medium Speed	High Speed
A constant speed is shown by a constant positive gradient.	A higher gradient means a higher speed.	The highest speed is shown by the steepest gradient.
Stationary	Accelerating	Decelerating
A gradient of zero shows the object is not moving.	Acceleration is shown by an increasing gradient.	Deceleration is shown by a decreasing gradient.

Example Calculations

The speed can be calculated from a distance time graph by reading the graph and using the equation Speed=Distance/Time.

Calculate the speed of the object in this 80 second journey. distance = 400m time = 80s \[Speed = {\tfrac{distance}{time}} \] \[Speed = {\tfrac{400}{80}} \] \[Speed = 5m/s \]	Calculate the speed of the object in the first 20 seconds. distance = 400m time = 20s \[Speed = {\tfrac{distance}{time}} \] \[Speed = {\tfrac{400}{20}} \] \[Speed = 20m/s \]
Calculate the speed of the object between 20 and 80 seconds. distance = 100m time = 60s \[Speed = {\tfrac{distance}{time}} \] \[Speed = {\tfrac{100}{60}} \] \[Speed \approx 1.7m/s \]	Calculate the average speed of the object for its journey. distance = 500m time = 80s \[Speed = {\tfrac{distance}{time}} \] \[Speed = {\tfrac{500}{80}} \] \[Speed = 6.25m/s \]