Unidades

UNITS AND CONVERSION FACTORS
E.J. ROSCHKE
PROPULSION DIVISION
JET PROPULSION LABORATORY

1

NOTE:
Many years ago I was given a copy of this document, prepared in handwriting, some time in
the early 1960’s. I did not know the author, E.J. Roschke. I have found it to be such a useful
reference that I decided to have an electronic version prepared. Recently, I spoke with Dr.
Roschke, nowretired from the Jet Propulsion Laboratory to learn of the document’s origin. In
the early 1960’s a group of research engineers, largely having backgrounds in mechanical
engineering, were engaged in the new field of electric propulsion. They experienced practical
annoyances with the mingling of units from mechanical engineering, electrical engineering and
physics. That situation motivated Dr.Roschke to assemble this material.
Although I have carefully checked the values given here, it is quite possible that some
typographical errors remain. I will appreciate learning any corrections that should be made.
F.E.C. Culick
Mechanical Engineering
California Institute of Technology
October 2001

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UNITS AND CONVERSION FACTORS
Table of Contents
Section
I.
II.
III.
IV.
V.VI.
VII.

Page

References
Decimal Multiples and Submultiples
Description of Units
Mechanical, Electric, Magnetic
Equivalent Units mksq System
Dimensions of esu and emu Electric
and Magnetic Quantities
Dimensions and Units for Physical Quantities — mksq System
A. Mechanical
B. Thermal
C. Electric and Magnetic
Conversion of mksq Units to Gaussian Units
Conversion Factors
A. PlaneAngle
B. Solid Angle
C. Length
D. Area
E. Volume
F. Mass
G. Density
H. Time
I. Speed
J. Force
K. Pressure
L. Energy, Work, Heat
M. Specific Energy
N. Specific Energy Per Unit Temp.
O. Power
P. Heat Flux
Q. Heat Transfer Coefficient
R. Thermal Conductivity
S. Absolute Viscosity
T. Kinematic Viscosity
AA. Electric Charge
BB. Electric Current
CC. Electric Potential
DD.Electric Resistance
EE. Electric Resistivity
FF. Capacitance
GG. Inductance

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3
4
4
5
5
6,7
6
7
7
8
8-23
8
8
9
9
9
10
10
11
11
11
12
13
14
15
16
17
17
18
19
19
20
20
20
21
21
21
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Table of Contents – continued
Section

VIII.
IX.
X.
XI.
XII.

Page

HH. Magnetix Flux
I I. Magnetomotive Force
J J. Magnetic Field Strength, B
KK. MagneticVector, H
Electromagnetic Constants of Free Space
Electromagnetic Constants of Materials
Some Important Dimensional Constants
Some Important Dimensionless Groups
The Perfect Gas Law
A. Nomenclature, Definitions and Equations
B. Values of Universal Gas Constant, Boltzmann’s Constant
and Avogadro’s Number in Different Units

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22
22
23
23
24
24
25
26
27,28
27
28

References usedin compiling these charts and tables are listed below in the order of “most
usage”.
1. Halliday, D. & Resnick, R., Physics – For Students of Science and Engineering, John Wiley,
New York, 1960.
2. Forsythe, W.E., Smithsonian Physical Tables, 9th Revised Edition, Publ. 4169, Smithsonian
Institution, Washington, D.C., 1954.
3. Scott, R.B., Cryogenic Engineering, D. Van Nostrand Inc.,Princeton, New Jersey, 1959.
4. Hall, N.A., Thermodynamics of Fluid Flow, Second Printing with revisions, Prentice-Hall
Inc., Englewood Cliffs, New Jersey, 1956.
5. Gray, D.E. (coordinating editor), American Institute of Physics Handbook, McGraw Hill
Inc., New York, 1957.
Additional Note on Use of Conversion Tables, Part VII.
Multiply units appearing in left-hand column by appropriate numericalfactor to obtain
units appearing in upper row.

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I.

DECIMAL MULTIPLES AND SUB-MULTIPLES
Name

tera
giga
mega
kilo
hecto
deca
II.

Symbol

Equivalent

Name

Symbol

Equivalent

T
G
M
k
h
−

1012
109
106
103
102
10

deci
centi
milli
micro
nano
pico

d
c
m
µ
n
p

10-1
10-2
10-3
10-6
10-9
10-12

DESCRIPTION OF UNITS
MECHANICAL UNITS...