Interpreting Motion Graphs

This lesson covers distance-time graphs and velocity-time graphs — as required by the Edexcel GCSE Physics specification (1PH0), Topic 2: Motion and Forces. You need to be able to interpret, draw and extract information from both types of graph, including calculating speed, acceleration and distance.

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Distance-Time Graphs

A distance-time graph plots the distance an object has travelled (y-axis) against the time taken (x-axis).

What the Shape Tells You

Shape of Graph	Meaning
Horizontal line	The object is stationary (not moving)
Straight line going up	The object is moving at constant speed
Steep straight line	Moving at a higher constant speed
Shallow straight line	Moving at a lower constant speed
Curve getting steeper	The object is accelerating (speeding up)
Curve getting shallower	The object is decelerating (slowing down)

Calculating Speed from a Distance-Time Graph

The gradient (slope) of a distance-time graph gives the speed:

Speed = Distance ÷ Time = Gradient of the line

For a straight line: choose two points, calculate rise ÷ run.