Introduction to Graphical Analysis
Objective: To use Graphical Analysis program to graph sets of data and find the line of best fit and to identify and
interpret the slope and y-intercept of this line.
Slope and y-intercept: The equation of a linear line is: y = mx+b. “m” is the slope of the line, and “b” is the y-
intercept.
Slope is a measure of how much a line rises or falls from one point on the line to another point on that line. The slope
will have units of the y axis divided by the units of x-axis.
To find the slope of a line using the math method:
The y-intercept is where the line crosses the y-axis. The y-intercept will have units of the y-axis.
Graphing y vs. x When graphing a y vs. x graph put the y values on the y-axis and the x values on the x-axis. For
example when making a “distance vs. time ” graph distance (m) goes on the y-axis and time (s) goes on the x-axis.
Using Graphical Analysis to plot a line
Using the computers in the Physics Lab (SM252) double click on the
physics folder that is located on the desktop. Inside that folder is
program called Graphical Analysis. Double click on that icon to start
the program. Double click on x column on the table and name the
x-axis Time and give it units of seconds or s.
Do the same for the y column name it Distance and give it units of
meters or m. Right click on the graph and select graph options and
title the graph Distance vs Time and uncheck connect points.
Now we need some data. Input these values in the table and
graphical analysis will automatically plot the graph from the values
that were entered. The graph will be linear. Instead of finding the
slope of this line using the math we can have Graphical Analysis find
it for us. In Graphical Analysis this is called a linear fit. Preforming a
linear fit will also give us the y intercept of the line.
