Forces and equilibrium - Orthopaedic Biomaterials in Research and Practice - page 2

Table 1.1 systems of basic units

System

SI a
(International
System)

CGS
(centimeter-gram-second) Units British (or English)

Length foot (ft) centimeter (cm) meter (m)

1 = 30.48 = 0.3048

0.03281 = 1 = 0.01

3.281 = 100 = 1

Mass pound (lb) gram (g) kilogram (kg)

1 = 453.6 = 0.4536

0.002205 = 1 = 0.001

2.205 = 1000 = 1

Time second (s) second (s) second (s)

Temperature degree

Fahrenheit (°F)

degree
Centigrade (°C)

degree
Celsius (°C)

1 = 0.5556 b = 0.5556 b

1.8 = 1 = 1

a

All examples and problems in this topic will use SI metric units since this is the Journal of Bone and Joint
Surgery editorial standard.

b

5/9 exact fraction.

Table 1.2 Prefixes for metric units

Prefix Abbreviation Multiply unit by

giga- G- 10 9

mega- M- 10 6

kilo- k- 10 3

deca- da- 10

deci- d- 10 -1

centi- c- 10 -2

milli- m- 10 -3

micro- μ- 10 -6

nano- n- 10 -9

pico- p- 10 -12

measurement to use and then by specifying the number of units required
to equal the patient's weight. In common terms, the “standard” patient
weighs 70 kg or 154 lb or even 11 stone.* The units and the quantity of
each required are different, but each combination gives us a quantitative
description of the patient's weight. To permit calculations to be done,
these units must be used together in compatible groups that will yield
correct results. The common systems in use and the basic units (and

* However, with the obesity epidemic in the United States and also in other countries,
what is considered a “standard” patient has changed.