Geoscience Reference
In-Depth Information
Appendix 2
Système International (SI) units
Quantity
Dimensions
SI
cgs metric
British
Length
L
m
10
2
cm
3.2808 ft
Area
L
2
m
2
10
4
cm
2
10.7640 ft
2
L
3
m
3
10
6
cm
3
35.3140 ft
3
Volume
10
3
g
Mass
M
kg
2.2046 lb
Density
ML
-3
kg m
-3
10
-3
g cm
-3
Time
T
s
s
Velocity
LT
-1
m s
-1
10
2
cm s
-1
2.24 mi hr
-1
Acceleration
LT
-2
m s
-2
10
2
cm s
-2
Force
MLT
-2
newton (kg m s
-2
)
10
5
dynes (10
5
g cm
-1
s
-2
)
Pressure
ML
-1
T
-2
N m
-2
(pascal)
10
-2
mb
Energy, work
ML
2
T
-2
joule (kg m
2
s
-2
)
10
7
ergs (10
7
g cm
2
s
-2
)
Power
ML
2
T
-3
watt (kg m
2
s
-1
)
10
7
ergs s
-1
1.340 10
-3
hp
Temperature
θ
kelvin (K)
°C
1.8°F
Heat energy
ML
2
T
-2
(or H)
joule (J)
0.2388 cal
9.470 10
-4
BTU
Heat/radiation flux
HT
-1
watt (W) or J s
-1
0.2388 cal s
-1
3.412 BTU hr
-1
Heat flux density
HL
-2
T
-1
W m
-2
2.388 10
-5
cal cm
-2
s
-1
The
basic SI units
are metre, kilogram, second (m, kg, s):
Temperature conversions
may be determined by noting
that:
1 mm = 0.03937 in
1 in = 25.4 mm
1 m = 3.2808 feet
1 ft = 0.3048 m
T
(°C)
T
(°F) - 32
——— = —————
5
1 km = .6214 miles
1 mi = 1.6090 km
9
1 kg = 2.2046 lb
1 lb = 0.4536 kg
1 m s
-1
= 2.2400 mi hr
-1
1 mi hr
-1
= 0.4460 m s
-1
1 m
2
= 10.7640 ft
2
1 ft
2
= 0.0929 m
2
Density units = kg m
-3
Pressure units = N m
-2
(= Pa); 100 Pa (=hPa) = 1 mb.
Mean sea-level pressure = 1013 mb (= 1013 hPa)
1 km
2
= 0.3861 mi
2
1 mi
2
= 0.5900 km
2
1°C = 1.8°F
1°F = 0.555°C