PASCO SE-9076 Constant Velocity Tubes - Manual (Page 9)

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Constant Velocity Tubes 012–06697B
3. It is useful to sketch a graph of the data as it is collected and examine the pattern as it forms.
Make a graph on the grid below using the data above, as follows:
a) Label the horizontal axis with the name of the independent variable (sometimes
called the “control” variable). Follow the name with the type of units of
measurement being used in parentheses ( ). In a similar manner, label the vertical
axis, which is used for the dependent variable.
b) Number the axes. Start numbering with zero at the origin (lower left corner).
➤ When numbering the axes, number the lines, not the spaces. Choose a
regular numbering system (e.g. by fives, tens, fifties, etc). Adopt a spacing
system that numbers every second, every fifth, or possibly every tenth line.
These choices make it easier to locate and plot data from metric system
measurements, as compared to systems involving numbering every three or
four lines. The numbering system chosen will depend on the largest
numbers that will need to be plotted.
c) Plot the data points. Make small, precise points. Then, because small points are hard
to find, make them more obvious by surrounding each point with a small circle,
triangle, or similar figure. These are called point protectors.
➤ If you feel uncertain about your work thus far, you should seek help
before proceeding.
➤ Drawing a graph as an experiment proceeds can help you to decide what
to do next. The two points plotted are just the beginning of a pattern.
Obtaining and plotting additional data points makes the pattern become
clearer.