Metric units in engineering--going SI : how to use the international sytems of measurement units (SI) to solve standard engineering problems

334 Pages·1995·11.63 MB·English

by  Cornelius Wandmacher

Metric Units in
Engineering
Going SI
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Metric Units in
Engineering
Going SI
REVISED EDITION
Cornelius Wandmacher, HE.
A. Ivan Johnson, EE.
With a new preface by
Christopher M. Stone, EE.
ASCE
PRESS
Library of Congress Cataloging-in-Publication Data
Wandmacher, Cornelius, 1911-1992.
Metric units in engineering - going SI: how to use the international system of measurement
units (SI) to solve standard engineering problems / Cornelius Wandmacher, A. Ivan Johnson.
- Rev. ed.
p. cm.
Includes index.
ISBN 0-7844-0070-9
1. Engineering mathematics. 2. Metric systems. I. Johnson, A.I. (Arnold Ivan). 1919- .
II. Title.
TA331.W36 1995 95-48550
620'.001 '530812—dc20 CIP
Published by American Society of Civil Engineers
1801 Alexander Bell Drive
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www.pubs.asce.org
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Original edition published in 1978 by Industrial Press, Inc.
Revised edition copyright © 1995 by the American Society of Civil Engineers.
Second impression, 2007
All Rights Reserved.
ISBN 13: 978-0-7844-0070-8
ISBN 10: 0-7844-0070-9
Manufactured in the United States of America.
Contents
Preface. vii
Preface to the First Edition ix
1. Introduction to SI 1
2. Statics 30
3. Dynamics 57
4. Strength of Materials 88
5. Mechanics of Machines 119
6. Fluid Mechanics 141
7. Thermodynamics and Heat Transfer 190
8. Electricity, Magnetism, and Light 225
9. Conversion to Preferred SI Usage 233
10. Moving into the World of SI 265
Appendix I 289
Appendix II 293
Appendix III 299
Metric Bibliography 305
Index 315
About the Author 321
V
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Preface
In today's global environment, metric measurements are prominent in workplaces,
consumer products, news reports, engineering, science, and technology. Almost
every country in the world uses the metric system of measurement and has enacted
legislation limiting international commerce solely to products measured in metric
units. If the United States is to continue to play a leading role in international
design and construction, the use of metric measurement is imperative, and U.S.
engineers at all levels must be knowledgeable and proficient with its application.
The version of the metric system known as the International System of Units,
or SI, was established by the General Conference on Weights and Measures
(CGPM) in 1960. Earlier versions of the metric system, such as the centimeter-
gram-second (COS) and meter-kilogram-second-ampere (MKSA), are no longer
acceptable and should not be used.
A summary of developments in the adoption of SI units in the United States
and Europe is included in the appendixes to this volume, but a few key dates may
be helpful to readers. In the United States, Congress made the metric system a
legal measurement system in 1866, but did not mandate its use. Enactment of
the Metric Conversion Act of 1975 established a national policy of voluntary use
of the SI version of the metric system. In 1988, this metric law was amended to
declare that SI units were the preferred measurement system for the United States
and directed federal agencies to make the transition to using SI by the end of fiscal
year 1992. Because some operations take longer to change over than others, the
transition to SI is an evolving process, but the transition is gradually taking place
in government, industry, and education.
In 1979, the European Union, then known as the European Economic
Community, approved a council directive specifying SI units as the legal units
of measurement in Europe and, more significantly, forbade the use of dual units
after 31 December 1999. As it become clear that the deadline was optimistic,
in January 2000 the ban on supplementary indications was postponed until 31
vii
viii PREFACE
December 2009. Beginning in 2010, it will generally be illegal to use dual units
in product brochures, manuals, advertisements, and engineering and technical
journals in the European Union.
The American Society of Civil Engineers kept pace with these changes, and in
1994 adopted Policy Statement 119, which actively supported the use of SI units
in civil engineering practice and research. The policy statement recommended
that no customary or outdated metric units be incorporated into the usage of the
modern metric system and that SI units be used as the primary unit of measurement
in all ASCE publications. It also encouraged civil engineering schools to stress the
use of SI units in instruction and in all books and instructional materials.
Cornelius Wandmacher published the first edition of this book with Industrial
Press, Inc., nearly 30 years ago. To support Policy Statement 119, A. Ivan Johnson
and ASCE's Committee on Metrication revised and updated Wandmacher's
original work. ASCE Press published this revised edition in 1995 to provide
guidance to practicing engineers, students, and educators who are adopting and
using SI units. Over the years, Metric Units in Engineering: Going SI has become
the definitive reference on the use of SI units in engineering. ASCE Press is now
issuing a new printing of this classic work, once again making this essential guide
available to the engineering community.
A few changes have taken place since 1995. Perhaps the most significant
pertains to ASTM E 380, Standard Practice for Use of the SI International
System of Units. In 1997, ASTM E 380 was replaced by IEEE/ASTM SI 10.
The new standard was developed and is maintained by professional industrial
organizations, namely the Institute of Electrical and Electronics Engineers (IEEE)
and the American Society for Testing and Materials (ASTM; now known as ASTM
International). It is approved by the American National Standards Institute as the
primary American National Standard on the metric system. Therefore, where the
text of this book refers to ASTM E 380, readers are encouraged to use IEEE/
ASTM SI 10 instead. In case of discrepancies or inconsistencies, IEEE/ASTM SI
10 would govern.
The United States continues to make progress in implementing the use of SI
units for more goods and services. ASCE's Committee on Metrication supports
efforts to make a transition to SI as the nation's primary measurement system and
to reestablish the U.S. Metric Board, which would support and encourage the use
of the metric system. The committee recognizes its leadership responsibility to
ensure that all engineers have the resources available to enable them to accurately
solve engineering problems using the metric system.
CHRISTOPHER M. STONE, P.E., F.NSPE, F.USMA
Member, ASCE Committee on Metrication
Chair, Certified Metric Specialist Program, U.S. Metric Association
Preface to First Edition
Intended for the use of practicing engineers and students who are
already knowledgeable in the area of engineering principles, this book is
meant to be of assistance in applying such knowledge to the solution of
typical problems but stated in terms of SI units.
Therefore it is anticipated that the reader will understand and observe
in each instance the limitations, if any, of the engineering principles and
procedures involved. Examples presented refer, in general, to common
or average conditions; the objective in particular is to illustrate, in the
most direct manner possible, the essential points to be observed in the
utilization of SI.
Since this book treats engineering principles broadly, it is not designed
to supplant standard texts or references on specific topics which should,
of course, be consulted for further interpretation of theoretical back-
ground as needed.
A key factor in the successful use of this book, however, will be found
in the emphasis on unit check-outs at intermediate and final solution
points in the computations. In addition to assuring consistency in the
usage of SI, the unit check-out process will rapidly increase the reader's
comprehension of SI as a highly desirable and coherent system for
engineering work. As will be noted, top priority is given to the
demonstration of SI as a new measurement system.
Thus, the following outline of problem solving procedure is recom-
mended:
(1) Select an applicable equation for conditions presented, and write it
down, using appropriate physical quantity symbols;
(2) To the right of this equation make a separate unit check-out using
appropriate SI unit symbols;
(3) Substitute numbers, in SI terms, for the given magnitudes of
physical quantities in the equation;
ix