Velocity-time graphs show how the velocity (or speed) of a moving object changes with time. These graphs also show if the object is moving at a constant speed or accelerating, decelerating, or still.

Key fact The gradient of speed-time and velocity-time graphs represent acceleration. The area under a speed-time graph represents the distance travelled.

Let's start with the definition of velocity (in one dimension): But what if I represent this as a graph? Here is a velocity vs time graph for this same situation.