ABSTRACT
At the end of this chapter, you should be able to:
• understand rectangular axes, scales and co-ordinates • plot given co-ordinates and draw the best straight line graph • determine the gradient of a straight line graph • estimate the vertical axis intercept • state the equation of a straight line graph • plot straight line graphs involving practical engineering examples
A graph is a visual representation of information, showing how one quantity varies with another related quantity. We often see graphs in newspapers or in business reports, in travel brochures and government publications. For example, a graph of the share price (in pence) over a 6month period for a drinks company, Fizzy Pops, is shown in Fig. 17.1. Generally, we see that the share price increases to a high of 400p in June, but dips down to around 280p inAugust before recovering slightly in September. A graph should convey information more quickly to the reader than if the same information was explained in words.
