# Speed-time graphs

**Speed-time graphs**

Travel graphs as shown below, can also be used to show the change in speed over time. For example, the graph below shows a cycle accelerating at a steady pace from rest to 20 m/s, it which point it continues as a constant speed for 15 seconds and then decelerates to a stead stop

**Finding acceleration from speed-time graphs**

The acceleration is calculated by dividing speed by time. Therefore the gradient = acceleration.

A zero gradient means that there is no acceleration.

**Finding distance from speed-time graphs**

The distance travelled is calculated by finding the area below the graph.

In the example above, the area is calculated using the formula to work out the area under a trapezium. Therefore:

Area = 0.5(15 + 40) x 20

Area = 550m