SM0486
LESSON 5.
WEIGHTS AND BALANCES
AIPD Subcourse Number SM0486...........Mechanical
and
Electro-Mechanical
Measurement Principles
Lesson Objective.......................Given learning objectives and supportive
text you should be able to answer all
exercise questions pertaining to mass and
its measurements, and the analytical (micro)
balance with no error.
Credit Hours...........................One
TEXT
1.
INTRODUCTION
The training information in this chapter is a continuation of your training in
the areas of length, mass, and time measurements. This chapter is designed to help
you increase your knowledge of the principles applied when weights and balances are
used in mass measurements.
A review of mass measurement principles is combined
with construction and operation principles to help you become proficient at your
job. The sections in this chapter teach the fundamental theories of mass and its
measurements; construction and operation principles for bullion balances; metric
analytical balances, and the weights associated with each type of balance.
2.
MASS AND ITS MEASUREMENT
a. The mass of an object is a measure of its inertia.
Inertia is usually
defined as that general property of matter which causes a body in motion to remain
in motion or a body at rest to remain at rest unless acted upon by an external
force.
Any discussion on mass and balances must also include a discussion of
weights, since in our gravitional environment any mass always exhibits the property
of weight.
The relationship between mass and weight is so inseparable that mass
determinations by means of comparing unknown weights to reference standards are
referred to as "weighing processes."
b. Mass Standards.
The metric standard of mass in the kilogram.
Smaller
units are used in the measurements you perform. Mass standards similar to the one
in Figure 1 are generally called weights.
The National Bureau of Standards, in
order to identify weights as to their general precision, stability, and use, has
set up classifications for different weights. Although not mandatory, this scheme
has found wide acceptance in commerce and industry. Weights, as described by NBS,
are divided into four basic classifications, which are:
(1) Precision Laboratory Standards.
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