Elise Livingston

## Measurements in Physics Lab

Dimension                         Metric Ruler                          Caliper

Outer Diameter                                         1.5 cm                                                  1.5 cm
15 mm                                                   15mm
Inner Diameter                                          1.3 cm                                                  1.3 cm
13 mm                                                  13 mm
Circumference                                            4.7 cm                                                 4.7 cm
Depth                                                                                                                          10.4 cm
Volume                                                       18.4 cm3                                             18.4cm3

Aluminum Square

Dimension                   Metric Ruler                   Caliper                    Micrometer

Length                                                2.4 cm                                     2.4 cm                                      2.4 cm
Width                                                  2.4 cm                                     2.4 cm                                       2.4 cm
Height                                                0.4 cm                                     0.4 cm                                    0.45 cm
Area                                                   5.8 cm2                                    5.8 cm2                                    5.8 cm2
Volume                                             2.3 cm3                                    2.3 cm3                                     2.6 cm3

Analysis Questions

1. Compare and contrast accuracy and precision. Consider how one could improve the accuracy of a     measurement? The precision of a measurement?

A: Accuracy is the degree of closeness that a particular measurement is to its actual value, while precision is the
degree to which multiple measurements are the same or similar. In order to improve the accuracy of a
measurement, tools could be used that would allow one to measure something to greater significant figures. For
instance, a micrometer would yield more exact measurements than a regular ruler would. To improve the
precision of a measurement or a set of measurements, it would be useful to measure everything in the same way
with the same tools. This would result in more similar measurements. If tools were used incorrectly, it would be
very possibly to have precise answers, but be very inaccurate.

2. Compare the number of significant figures in the calculartions and measurements taken with the       ruler to the measurements taken with the caliper and micrometer. Discuss the differences in               precision of these instruments.

A: The number of significant figures that  our group obtained were the same from both the ruler and the caliper. The        micrometer, however, yielded measurements past the tenths place of the decimal. The majority of our
measurements were two significanfigures. The ruler and the Vernier Caliper yielded the same results, therefore,
making them the most precise of thtools. The micrometer may have been the most accurate, but because it
yielded slightly different results, it was thleast precise.

3.  Compare your measurements and calculations with those of a classmate. Are they the same?              Discuss sources of error in the accuracy of the measurements.

A: When our results were compared to another group's, we found that the other group had obtained more
significant figures than ours. This is because our group chose to record fewer significant figures and round, as the
other group chose to guess to another decimal place. Their results may have turned out more accurate, but ours
were fractionally more precise. Throughout both groups, the measurements on the graduated cylinder were very
precise. However, the measurements of the Aluminum square became less and less precise. In some cases, our
measurements varied as much as .1 to .3 cm. This drastic variation could be due to several things. The aluminum
squares may not have been consistent in size, or the change could be due to human error on the part of one of us.

4. Which instrument is more precise, the metric ruler, the caliper or the micrometer?

A: The caliper and the ruler seemed to be the most precise of the tools in this experiment, while the micrometer
was the most accurate only as it yielded more significant figures. However, all of the tools did obtain very precise
measurements throughout the experiment.