Quick links on this page: | Introduction | Micrometer | vernier | Toolbar | Density |
OBJECTIVES:
NOTE: This experiment illustrates the earlier sections on Errors and Significant Figures. The actual density of the metal is incidental. However, the accuracy of your estimate of reliability will show whether you have mastered the material in the earlier sections.
APPARATUS:
You should be able to complete this brief quiz before proceding.
PRECAUTIONS:
INTRODUCTION:
THE MICROMETER:
THE VERNIER CALIPER:
Precautions on use of the calipers:
CALIBRATION OF THE MICROMETER (or VERNIER, ETC.):
DENSITY DETERMINATION:
Related facts and URL links:
Answer(not verified): The Treaty of the Meter (Convention du Metre) in the
late 19th century
established the first centralized international system of metrology. This
defined the meter.
In 1959, the countries of the world that were using Imperial units defined them
uniformly based on the metric units. The inch was simply defined that way and
agreed to by all. Before 1959, different countries related inches to meters in
other ways. Among them was the United States. The Metric Act of 1866 defined
the meter in terms of inches (i.e., before the Treaty of the Meter), and that
relationship had continued to been used even after the Treaty fixed the length
of the meter.
Changing the definition in the U.S. in 1959 caused very little problem,
except for the U.S. Geological Survey. When you deal with things 10
meters big (like the sizes of the states), even 1 part in 10
changes
affect the specifications of boundary lines in significant ways. So, to
this day the U.S. has two different systems of inches, feet, and yards (in
the ratio of 36:3:1, for both). There's the usual inch, foot, and yard;
and there's the survey foot (and inch and yard), which is based on the
pre-1959 definition. (The ambiguity goes away, of course, when metric
specification is used. Newer USGS maps are metric.)
Links to metrology site(s):
National Institute of Science &
Technology