Graphing and the Measurement of Mass



Graphing and the Measurement of Mass©98

Experiment 1

Objective: To determine the mass of an object using a graphical method which does not depend upon the weight of the object. To present this and other information in a graphical manner according to a logical set of standards.

Discussion:

Data observed in laboratory experiments are most desirably recorded in a somewhat orderly tabular fashion. One can sometimes examine the table of values and notice trends, or relationships, between the variables in the experiment. However, much easier interpretations result when the depiction of the data is dramatically presented in the form of a graph – provided good graphing habits have been followed. One purpose of this experiment is to develop good graphing habits in order to obtain information easily from a graph. Some brief comments that apply to all graphs:

• In most experiments, there is a cause (the independent variable- the experimenter usually controls this perhaps calling it a parameter) and effect (the dependent variable- the measure results). The idea is to observe the change in a dependent variable when the independent “control” variable is changed.

• On a graph, the independent variable should be plotted upon the x-axis, with the dependent variable on the y-axis.

• The axes should be drawn inside the margins of the graph paper with the intersection of the axes located in the lower left. This leaves room to neatly write in a scale, the names and units of the variables.

• Be sure to choose a scale such that the entire sheet accommodates the entire range of values. Take the largest value, divide by the total number of divisions available. Now round up so that the subdivisions will be a multiple of 2, 5 or 10. Four is occasionally tolerable, rarely 8. Multiples of 3, 7, 9, 11 and higher should be avoided, since they make smaller divisions nearly impossible to read.

• Neatly label each axis, with the units abbreviated. Write in the scale at major divisions on the graph paper. Put in a title (after the curve is plotted) in a position in the upper center or upper right of the page.

• Use sharp, fine pencil to make small dots indicating data points. Draw small ................
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