GRAPHINGAlgebraThe first step is to label the x-axis and the y-axis. Let the x-axis be temperature in °C andthe y-axis be density in g/ml.The next step is to establish the units of measurement along each axis. The x-axis mustrange from approximately 40 to 100, the y-axis from 0.95 to 1.00.The points are then plotted one by one. Figure 3 shows the resulting Cartesian coordinategraph.Figure 3 Cartesian Coordinate Graph of Density of Water vs. TemperatureGraphs are convenient because, at a single glance, the major features of the relationship betweenthe two physical quantities plotted can be seen. In addition, if some previous knowledge of thephysical system under consideration is available, the numerical value pairs of points can beconnected by a straight line or a smooth curve. From these plots, the values at points notspecifically measured or calculated can be obtained. In Figures 2 and 3, the data points havebeen connected by a straight line and a smooth curve, respectively. From these plots, the valuesat points not specifically plotted can be determined. For example, using Figure 3, the densityof water at 65°C can be determined to be 0.98 g/ml. Because 65°C is within the scope of theavailable data, it is called an interpolated value. Also using Figure 3, the density of water at101°C can be estimated to be 0.956 g/ml. Because 101°C is outside the scope of the availableMA-02 Page 76 Rev. 0
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