534
APPENDIX A. METRIC (SI) SYSTEM
the conversion factor. For example, to convert 30.4 cubic yards to cubic
meters:
30.4 yd3 x 0.764 555 = 23.2 m3
Conversions of metric quantities into their equivalent English units can
be done by dividing the metric value by the appropriate conversion factor
given in Table A.4.
In Table A.4 pound-mass (or ounce-mass) refers to the British Type II
system where mass is a base unit and force is given as pound-force. In the
British Type I system mass is given in slugs and force is a base unit given
in pounds. At sea level:
1 pound-mass (Type II) = 1 pound-force (Type II) = 1 pound (Type I)
A.8 Temperature Conversion
The conversion from degrees Fahrenheit to degrees Celsius is given by
°C = -(° F-32°)
y
which can be arranged to give the conversion from degrees Celsius to degrees
Fahrenheit as
Q
°F = - (°C) + 32°
5
A.9 Significant Digits
When converting quantities from English to SI units, care must be taken
to retain a sufficient number of significant digits to reflect the accuracy of
the original quantity. Conversions obtained using conversion factors, generally imply a greater accuracy than the original value. Thus, the converted
number should be rounded to the proper degree of accuracy. For example, a linear measurement of 14.3 feet converts to 4.358 64 meters, but the
original measurement is obviously not this accurate. Therefore the result
should be rounded to 4.36 meters because 0.1 feet is about 0.03 meters. In
other words, linear measurements made to the accuracy of 0.1 feet using
English units could be made to an accuracy of about 0.03 meters using SI
units. The same consideration should be made when converting approximate quantities. For instance, 300 000 cubic yards of fill material converts
to about 230 000 cubic meters instead of 229 366 cubic meters.
APPENDIX A. METRIC (SI) SYSTEM
the conversion factor. For example, to convert 30.4 cubic yards to cubic
meters:
30.4 yd3 x 0.764 555 = 23.2 m3
Conversions of metric quantities into their equivalent English units can
be done by dividing the metric value by the appropriate conversion factor
given in Table A.4.
In Table A.4 pound-mass (or ounce-mass) refers to the British Type II
system where mass is a base unit and force is given as pound-force. In the
British Type I system mass is given in slugs and force is a base unit given
in pounds. At sea level:
1 pound-mass (Type II) = 1 pound-force (Type II) = 1 pound (Type I)
A.8 Temperature Conversion
The conversion from degrees Fahrenheit to degrees Celsius is given by
°C = -(° F-32°)
y
which can be arranged to give the conversion from degrees Celsius to degrees
Fahrenheit as
Q
°F = - (°C) + 32°
5
A.9 Significant Digits
When converting quantities from English to SI units, care must be taken
to retain a sufficient number of significant digits to reflect the accuracy of
the original quantity. Conversions obtained using conversion factors, generally imply a greater accuracy than the original value. Thus, the converted
number should be rounded to the proper degree of accuracy. For example, a linear measurement of 14.3 feet converts to 4.358 64 meters, but the
original measurement is obviously not this accurate. Therefore the result
should be rounded to 4.36 meters because 0.1 feet is about 0.03 meters. In
other words, linear measurements made to the accuracy of 0.1 feet using
English units could be made to an accuracy of about 0.03 meters using SI
units. The same consideration should be made when converting approximate quantities. For instance, 300 000 cubic yards of fill material converts
to about 230 000 cubic meters instead of 229 366 cubic meters.