Distance–Time and Velocity–Time Graphs — AQA GCSE Physics

Motion graphs are a powerful way to represent and analyse how an object moves.

Distance–time graphs

A distance–time graph shows how distance changes with time:

• The gradient (slope) gives the speed.
• A horizontal line means the object is stationary.
• A straight, sloping line means constant speed.
• A curved line means the speed is changing (accelerating or decelerating). The speed at a point is the gradient of the tangent.

Velocity–time graphs

A velocity–time graph shows how velocity changes with time:

• The gradient gives the acceleration.
• A horizontal line means constant velocity (zero acceleration).
• A line sloping up means acceleration; sloping down means deceleration.
• The area under the line gives the distance travelled.

Calculating from graphs

• Speed = gradient of a distance–time graph.
• Acceleration = gradient of a velocity–time graph.
• Distance = area under a velocity–time graph.

Exam tips

• Distance–time: gradient = speed; flat line = stationary.
• Velocity–time: gradient = acceleration; area = distance.
• A curved distance–time graph means changing speed (use a tangent).
• Be able to calculate gradients and areas (split into triangles and rectangles).