TABLE OF CONTENTS Dimensions are names used to describe the characteristics of a physical quantity. Examples of dimensions are length, mass, time, temperature, and electric charge. Units are the basic standards of measuring the magnitudes of physical quantities. For example, meter is a unit for the measurement of length, and second is a unit for measuring time. Units are two types : fundamental and derived. Fundamental units are independently defined whereas the derived units are expressed in terms of the fundamental units. Various unit systems differ from one another in the choice of fundamental dimensions and units (Table 1-1).
| Metric or | |||||
|---|---|---|---|---|---|
| SI system: | British | USCS | |||
| Dimension: | Symbol | Unit | Unit | Unit | |
| Length | L | Meter | foot | foot | |
| Mass | M | kg | slug [*] | lb m | |
| Time | t | Second | Second | Second | |
| Temperature | T | degree K | F | F | |
| Force | F [*] | Newton (N) [*] | poundal | lb f | |
| [*]denotes a derived unit in the system |
In the SI system, 1 Newton = ( 1 kg ) x (1 m / s 2 )
In British Engineering system, 1 slug = 
In fps system, 1 poundal = (1 lb-mass) x (1 ft/s 2)
Comparison of British and fps systems shows:
1 slug = 32.174 lb m
1 lb-force (lb f) = 32.174 poundals
The US customary system,
where Newton's law proportionality factor g c = 32.174 lb m.ft/s 2.lb f
A mole of a substance =...
