Distance-Time Speed-Time Graphs

Distance – Time Graph

Time is in the x axis. Distance is in the y axis.

Speed is the gradient of the graph.

Speed - first part of the journey = (25 - 0) / (10-0) = 2.5 m/s

Speed - second part of the journey = (40 - 25) / (20 - 15) = 3 m/s

Average Speed = Total distance travelled/ total time = 40/20 = 2 m/s

Speed – Time Graph

Time is in the x axis. Speed is in the y axis.

Distance travelled is the area under the graph.

Acceleration is the gradient.

Distance travelled - first part of the journey

= (1/2) x 50 x 30 = 750 m


Distance travelled - second part of the journey

= 30 x 30 = 900 m


Distance travelled - third part of the journey

= (1/2) x (40 + 30) x 20

= (1/2) x 70 x 30 = 1050 m


Average Speed = Total Distance travelled/ total time

= (750+900+1050) / 100

= 2700/100 = 2.7 m/s