Travel graphs The two types of graphs you will meet are distance/time and speed/time. Time is almost always plotted on the x-axis! Distance/time If you show a graph of a journey showing distance travelled (on the y-axis) against time (on the x-axis): 1. The gradient (or slope) of the graph represents the speed. 2. A horizontal section indicates that you have stopped. 3. A section sloping up means you are going away. 4. A section sloping down means you are coming back. 5. The steeper the line, the faster you are going. Speed/time 1. The gradient (or slope) of the graph represents the acceleration. 2. The area under the graph (for any section) is the distance travelled (in that section). 3. A horizontal section indicates constant speed (no acceleration). 4. A section sloping up means accelerating. 5. A section sloping down means slowing down. 6. The steeper the line, the quicker the acceleration. Graphs to represent data Graphs used to represent data include: Bar charts (sometimes called frequency diagrams) Line graphs Frequency polygons Cumulative frequency graphs Scatter diagrams These are all covered in the section Representing Data.