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

National 5 Velocity-time graphs Velocity, speed and acceleration Velocity-time graphs are used to describe the motion of objects which are moving in a straight line.

On the left side, P is traveling with a constant speed; as discussed above, there is a 90 degree angle between velocity and acceleration. On the right side, P moves with increasing/decreasing speed.