Importance of Unit System and Unit Conversion
Sept 24, 1999
Mars Orbiting Craft Presumed Destroyed By Navigation Error
Unit Systems and Conversions
October 1, 1999
Two Teams, Two Measures Equaled One Lost Spacecraft
http://www.mactonnies.com/spiritmer.jpg
By Andrew Pollack, New York Times.
Lecture 2
Fall Semester 2011
SOCR 377 / 577
LOS ANGELES -- Simple confusion over whether measurements were metric or not
led to the loss of a $125 million spacecraft last week as it approached Mars, the
National Aeronautics and Space Administration said on Thursday.
Lockheed Martin Corporation which had built the spacecraft, specified certain
measurements about the spacecraft's thrust in pounds, an English unit, but that
NASA scientists thought the information was in the metric measurement of
Newton.
Important units…
Important units
Length
Mass
103
1 in = 2.54 cm
1 kg =
1 ft = 12 in = 30. 48 cm
1 gm = 10-3 kg
gm
1 yd = 3 ft = 91.44 cm
1 kg = 2.205 lbs
1 m = 1.0936 yd = 3.281 ft = 39.37 in
1 lbs = 454 gm
1 mi = 5280 ft = 1760 yd
1 oz = 28.4 gm
1 mi = 1.609 km
1 ton = 2000 lbs
1 light year = 9.461 x
1015
m
Area
Volume
1 in2 = 6.4516 cm2
1 in3 = 16.39 cm3
1 ft2 = 9.29 x 10-2 m2
1 ft3 = 1728 in3
1 cm2 = 10-4 m2
1 gal = 4 qt = 8 pt = 128 oz = 231 in3
1 acre = 43, 560 ft2
1 gal = 3.786 lit
1 mi2 = 6430 acres = 2.59 km2
1 lit = 1000 cm3 = 10-3 m3
Time
1 mt = 2205 lbs
Speed
1 h = 60 min = 3600 sec
1 ft/sec = 0.3048 m/sec
1 d = 24 h = 1440 min = 8.64 x 104 sec
1 mi/h = 0.4470 m/sec
1 y = 365.24 d = 3.156 x 107 sec
1 mi/h = 1.467 ft/sec
Speed of light = 186,300 mi/sec (in vacuum)
Speed of light = 300,000,000 m/sec
Important units…
Important units…
Conversion Factors for SI and non-SI Units
To convert Column 1
into Column 2,
multiply by
Column 1
SI Unit
Conversion Factors for SI and non-SI Units
Column 2
non-SI Unit
To convert Column 2
into Column 1,
multiply by
Length
To convert Column 1
into Column 2,
multiply by
Column 1
SI Unit
Column 2
non-SI Unit
To convert Column 2
into Column 1,
multiply by
1.609
Length
0.621
kilometer, km (103 m)
mile, mi
1.609
0.621
kilometer, km (103 m)
mile, mi
1.094
meter, m
yard, yd
0.914
1.094
meter, m
yard, yd
0.914
3.28
meter, m
foot, ft
0.304
3.28
meter, m
foot, ft
0.304
(10-6m)
1.0
micrometer, μm
3.94 x 10-2
millimeter, mm (10-3m)
10
nanometer, nm
(10-9m)
(10-6m)
micron, μ
1.0
1.0
micrometer, μm
inch, in
25.4
3.94 x 10-2
millimeter, mm (10-3m)
Angstrom, Å
0.1
10
nanometer, nm
(10-9m)
micron, μ
1.0
inch, in
25.4
Angstrom, Å
0.1
Important units…
Important units…
Conversion Factors for SI and non-SI Units
Prefixes for decimal fractions and multiples
Yield and Rate
Decimal fraction
Prefix
Abbreviation
10-18
Atto
a
Example
atto-meter
10-15
Femto
f
femto-meter
10-12
Pico
p
pico-gram 9pg)
10-09
Nano
n
nano-meter (nm)

micro-gram (g)
0.893
kilogram per hectare, kg ha-1
pound per acre, lb acre-1
7.77 x 10-2
kilogram per cubic meter, kg m-3
pound per bushel, bu-1
12.87
1.49 x 10-2
kilogram per hectare, kg ha-1
bushel per acre, 60 lb wheat
67.19
10-06
1.59 x 10-2
kilogram per hectare, kg ha-1
bushel per acre, 56 lb corn
62.71
10-03
1.86 x 10-2
kilogram per hectare, kg ha-1
bushel per acre, 48 lb barley
53.75
10-02
Billionth part
Micro Millionth part
Milli Thousandth
Centi Hundreth
0.107
liter per hectare, L ha-1
gallon per acre
9.35
10-01
893
tonnes per hectare, t ha-1
pound per acre, lb acre-1
1.12 x 10-3
101
1.12 x 10-3
102
103
106
Mega
109
Giga
G
giga-hertz (Ghz)
1012
Tera
T
tera-grams (Tg)
893
megagram per hectare, Mg ha-1
pound per acre, lb acre-1
1.12
0.446
megagram per hectare, Mg ha-1
ton (2000 lb) per acre, ton acre-1 2.24
2.24
meter per second, m s-1
mile per hour
0.447
Problem Questions In Handout
Longitude
m
milli-meter (mm)
c
centi-meter (cm)
Deci
d
deci-liter (dl)
Deka
da
deca-gram (dag)
Hecto
h
hecto-liter (hl)
Kilo
k Kilo bytes, 1000bytes kilo-grams (kg)
M1000,000 bytes
mega-byte (Mb)
Latitude
Grid System
Problem Questions In Handout
In 2006, daylight time begins on April 2 and ends on October 29.
In 2007, daylight savings time begins on March 11 and ends on November 4. [New law went into effect.]
In 2008, daylight savings time begins on March 9 and ends on November 2.
In 2009, daylight savings time begins on March 8 and ends on November 1.
In 2010, daylight savings time begins on March 14 and ends on November 7.