Graphing Rules
One of the most useful methods of discovering the relationship between two sets
of data (two variables) is by graphing the results of an experiment in which one
quantity is varied, the resultant variation in the second quantity is noted, and all
other factors are held constant.
Guidelines for Graphing
1. Be Neat. Always use a pencil.
2. Plot the independent variable (the controlled variable) on the X –AXIS
(horizontal) and the dependent variable (the result or change due to the
variation) on the Y –AXIS (vertical).
3. Chose a scale so that one block on the graph paper = 1, 2, 5, or 10 (never
use 3 or 7 or 9 etc.)
4. Scales should be chosen and numbered so the graph covers as much of the
paper as possible using the data you have ( you might not always start at
zero)
5. Label the graph: tell what the experiment goes with, give quantities
represented, and give units.
6. Don’t number every block on the graph paper. Number every 2nd, or 4th or
5th
7. Each point can have an “error circle” in order to allow for errors in plotting
or small errors in data
8. Unless there is some specific reason not to do so, draw a smooth line
through the points --- don’t go from point to point with small straight lines.
If in your judgment it appears as a straight line, the line need not go exactly
through each and every point, likewise a smooth curve will not generally
connect each and every point. Judgment must be exercised since making
the curve follow each point may make bad data appear as good data. On
the other hand, good data with real variations may appear and not be
recognized if the curve is carelessly plotted as an average.
9. Good judgment must be exercised in applying these rules.
Use graph paper to plot the following Data sets.
I.
Force
( lbs)
0
1
2
3
4
5
6
III.
A Rubber Band Being Stretched
Stretch
(cm)
0.0
0.6
1.2
1.8
2.4
3.0
3.6
Radius ( M )
6
14
28
36
50
Moving Car
Time ( Seconds)
0
1
2
3
4
II. Model Airplane Flying in a Circle
Distance ( M )
0
5
20
45
80
Force on String ( Netwons)
30
25
16
11
2
IV. Boyles Law
Pressure ( atm )
0.1
0.2
0.3
0.5
0.7
1.0
Volume ( L )
225
110
75
45
32
22