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
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