2. Chapter 5- Metric
This chapter will explore another system of measurement
called the metric system. This system of measurement
formerly called the “International System of Units” (SI) is
simply a group of terms used to describe fundamental
quantities such as length, weight, time and other values.
The metric system of measurement is being adopted by more
and more countries every year. In the United States many
industries are converting to the metric system so they can be
competitive in foreign markets.
3. Chapter 5- Metric
Doctors use metric units for prescribing doses or quantities of
medicine and drugs. Many food processing industries are marking
both metric and U.S. customary units on food packages. If you have
not already been exposed to metric measurements it is almost
certain you will begin using metric measurements.
This chapter introduces the terms and calculations of the metric
system. The metric system is not very complicated and should not
be too difficult to learn — the hard part will be unlearn lag or
momentarily forgetting the other systems of measurement with
which you may be familiar. To help you get started remember that:
A meter is a yard — plus a little extra.
A kilogram is two pounds — plus a little extra.
A liter is a quart — plus a little extra.
4. Chapter 5- Metric
The International System of Units —
officially abbreviated SI — is an updated
and expanded version of the metric system.
It was established by international
agreement to provide a logical framework
for all measurements in science, industry,
and commerce. SI is built on a foundation
of base units. What are these units?
6. Chapter 5- Metric
2. Now that you know the basic metric units
you will be using — the meter, kilogram
and liter. And you know about how much
each unit amounts to — the meter about a
yard, the kilogram about 2 pounds, the liter
about a quart. What happens if you want to
measure something much larger, or
smaller, than these three amounts?
7. Chapter 5- Metric
The metric system is easy to work with because it
is based on 10. You can multiply or divide the
base units by 10 by using a system of prefixes,
and simply moving the decimal point around. The
same prefixes are used for all three units. The
meter will he used to show the relationship. See
Fig 5-1. The prefixes given in red are those you
will use the most, the others are included so you
can see the way the 10 system works up and
down from the base unit.
9. Chapter 5- Metric
3. The metric system term for miles is
kilometer. The term for yards and feet is
meters. What is the metric system term for
inches?
The metric system term for inches is
centimeter. For very small measurements
the term is millimeter.
10. Chapter 5- Metric
You must remember to think 10. The whole
system depends on it. Ten millimeters
equal 1 centimeter, 10 centimeters equal 1
decimeter, 10 decimeters equal 1 meter, 10
meters equal 1 dekameter, 10 dekameters
equal 1 hectometer, 10 hectometers equal
1 kilometer. The symbols for these terms
are:
12. Chapter 5- Metric
It has been established, the same SI
prefixes are used throughout the system, to
make the base unit larger or smaller as
needed. The kilogram is a base unit but it
already has a prefix kilo. Explain.
13. Chapter 5- Metric
This is something you have to get accustomed to,
and remember that the kilogram is the one and
only exception to the prefix rule.
The gram (which would normally he the base unit)
is such a small amount of weight (about as much
as a paper clip), that working with it would be very
difficult. Therefore, the use of the kilogram as the
base unit has evolved.
You will mainly use the kilogram and the gram,
and may come in contact with the milligram (in
medicine dosages, for example).
14. Chapter 5- Metric
The same rule of thinking 10 applies. Ten
milligrams equal 1 centigram, 10
centigrams equal 1 decigram, 10
decigrams equal 1 gram, 10 grams equal 1
dekagram, 10 dekagrarns equal 1
hectogram, 10 hectograms equal 1
kilogram. The symbols for these forms are:
16. Chapter 5- Metric
5. To measure weights in the metric
system, journeyworkers normally use the
kilogram (except for small amounts,
perhaps up to 2 pounds). They also may
find a measure called a metric ton to weigh
large objects. A metric ton equals 1000
kilograms. What will journeyworkers use to
measure quarts and gallons?
17. Chapter 5- Metric
Where they now measure in quarts and
gallons, journeyworkers will use liters.
Liquid measures will be defined in milliliters
(ml); milliliters will be used instead of
ounces. The liter follows the prefix rule as
shown below:
18. Chapter 5- Metric
6. Following is a quick review of information which is
important for you to know? You will need to know about the
vieter. It’s a little more than a yard long. Its symbol is m. You
will use the meter (it) to measure things you now measure in
yards and feet. You will use the kilometer (km) to measure
what you now measure in miles. And you will use the
centimeter (cm) to measure inches. You may also use the
millimeter (mm) for this type of length measure. Another unit
to remember is the kilogram. It’s a little more than 2 pounds.
Its symbol is kg. You will use the kilogram to measure what
you now use pounds for. You will use the gram (g) to
measure smaller weights, ounces and perhaps up to 2
pounds. What is another important unit for you to know?
19. Chapter 5- Metric
Another important unit to know is the lite;c
It’s a little more than a quart. Its symbol is
1. You will use the liter to measure liquids
you now measure in quarts and gallons.
The only other form you will probably ever
come in contact with is the milliliter (ml),
used for smaller quantities.
20. Chapter 5- Metric
7. What are three prefixes and their meaning you
will need to remember?
Three prefixes are:
1. Milli — means one thousandth of whichever
unit you are measuring.
2. Centi — means one hundredth of whichever
unit you are measuring.
3. Kilo — means one thousand of whichever unit
you’re measuring.
21. Chapter 5- Metric
8. Metric math is simple. Because the whole
metric system is based on 10, the problems of
multiplying and dividing you will need to do are
simple. For all practical purposes, fractions and all
of the problems connected with working with them
are eliminated in the metric system. You will no
longer have to contend with fractions, which have
no easy relationship to each other. Explain.
22. Chapter 5- Metric
Simply remember this — when you are
working from a base unit to smaller units,
move the decimal point to the right. When
you are working from the base unit to larger
units, move the decimal point to the left,
Use the meter as an example.
23. Chapter 5- Metric
Note: If you are working with area (some
measure squared) or with capacity (some
measure cubed), remember that you move
the decimal point 2 places (square
measure) or 3 places (cubic measure) for
every one move in straight measure.
24. Chapter 5- Metric
9. An important factor in the use of the
metric system is its simplicity. With a little
care in using terms and symbols correctly,
the system can be clearly understood by
everyone. List a few basic rules to
remember.
A few basic rules are:
25. Chapter 5- Metric
1. Metric unit names are never capitalized,
with one exception — degree Celsius.
2. The symbols for the metric units you will
use every day are rarely capitalized either
(except for °C, A, W). For example, it
should always be nun for millimeter, never
MM or Mm. There are some scientific units
which require capitalized symbols, but the
everyday units do not.
26. Chapter 5- Metric
3. Unit symbols are never made plural with
the addition of a final -s. The symbol
remains the same, whether used for a
single unit, or for several units. For
example:
1 mm
5 mm, not 5 mms
27. Chapter 5- Metric
4. Never use any of the prefixes alone to
indicate a metric unit. It is incorrect usage,
and confusion could result. For example:
you travel 12 kilometers, never 12 kilos and
you buy one kilogram of butter, not one
kilo.
28. Chapter 5- Metric
5. When writing the symbols, don’t put
periods after them, except at the end of a
sentence. For example: The man is 180 cm
tall, (not 180 cm.)
6. Always leave a space between numerals
and symbols used with them. For example:
10 cm, not 10cm
29. Chapter 5- Metric
7. When writing large numbers, use spaces
to separate the groups of three numerals
now separated by commas. For example:
10 000 000, not 10,000,000
8. Always use a zero before a decimal
quantity when it is less than one unit, For
example: 0.55, not .55
30. Chapter 5- Metric
9. When expressing an amount like kilometers per
hour or meters per second, use the slash as
follows:
kilometers per hour = km/h
meters per second = m/s
10. Don’t try to improve on the SI, try to think in
metric terms, and spend as little time as possible
converting back and forth from the metric system
to the English system.
31. Chapter 5- Metric
10. The real secret in understanding the metric system is to
learn to think metric. The only time people seem to have real
difficulties with learning metric concepts is when they insist
on converting every figure they see back to customary
measures. Try to do as little of that as possible. Use the
information on the metric system which has been discussed
so far, and avoid conversions whenever you can. For the
most part, you just won’t need them. But, for those occasions
(which will occur) when you do need to make a simple
conversion, some basic conversion factors are listed below.
33. Chapter 5- Metric
List some conversion factors which could
be used to go the opposite way.
Note: If you want to figure area or volume,
the mathematic process is exactly the
same, whether you are figuring in feet and
yards or in meters or anything else in the
metric system.
36. Chapter 5- Metric
11. What is the advantage that SI possesses in
comparison with the English system?
The advantage of SI is that all multiples and sub-
multiples (divisors) of the measurement units
(base units) are based on 10. You can multiply or
divide the base units by 10 using a system of
prefixes and simply moving the decimal point
around. See Table A in Appendix B. Micro, milli,
centi, kilo, and mega are prefixes used with all of
the base units of measure and weight. The value
of the prefixes as multipliers and divisors does not
change from unit to unit.
37. Chapter 5- Metric
12. The measure of distance concerns the
journeyworker the most, so it is the logical
starting point. The standard measure of
length in the English system is the foot,
containing 12 inches. What is the standard
length measurement of SI?
38. Chapter 5- Metric
The standard metric measure of length is the
meter (m). The original meter was computed to he
one ten-millionth of the distance from the North
Pole to the equator measured along a meridian
line. The meter was electronically refined and is
now defined as a definite number of wavelengths
of the orange-red radiation of krypton 86. Instead
of relying on metal bars kept in the U.S. Bureau of
Standards, the standard meter length for
calibration purposes can he produced
electronically in the laboratory.
39. Chapter 5- Metric
13. Compare the meter to the foot.
See Fig. 5-2. The meter is 39.37 in. long.
This length equals 3.28 ft. These
comparisons and other base unit
conversions are given in table form in
Appendix B.
41. Chapter 5- Metric
14.
Compute the conversion factor for
changing meters to yards.
42. Chapter 5- Metric
15. One kilometer equals 1,000 meters.
One meter equals 1.09 yards. Convert one
kilometer to yards.
43. Chapter 5- Metric
16. Earlier study units have illustrated some
of the advantages of the metric system. All
the units are multiples or divisors of 10,
100, or 1,000 and are based on the decimal
system. See Table A in Appendix B. What
is the prefix for 1,000?
The prefix is kilo.
44. Chapter 5- Metric
17. The meter is divided into 100 parts called
cciithucters. In each centimeter, there are 10
divisions called millimeters. How many millimeters
are there in one meter?
There are 1,000 millimeters in one meter. A
centimeter equals .39 in. (approximately % in.)
and a millimeter equals .039 in. (approximately %.
in.). To get the proper accuracy on the job,
measurements should be taken to the closest
millimeter See Fig. 5.3.
46. Chapter 5- Metric
18. Since SI uses the base 10 decimal
system, placement of the decimal point and
labeling of units becomes vital in recording
the results of job computations. What units
of SI length are most commonly used by a
journeyworker on the job?
The two most commonly used SI length
units will be the meter (m) and the
centimeter (cm).
