Real-life Graphs

The two types of graphs you will meet are distance/time and speed/time.

Time is almost always plotted on the x-axis!

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.

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 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.