The distance graph shows the height of a plane as it completes a journey. When the plane is at a height of 38,000 feet (ft), it travels at a constant speed of 550 miles per hour. The question asks ...

Example: Using the gradient or slope of a distance - time graph to work out the speed of an object Calculate the speed of the object represented by the green line in the graph below, from 0 to 3 s.