ABSTRACT
Before we begin the exciting study of ¡uid mechanics, it is prudent to discuss dimensions and units. In this text, we use two unit systems: the British gravitational system and the international system (SI). Whatever the unit system, dimensions can be considered as either fundamental or derived. In the British system, the fundamental dimensions are length, time, and force. The units for each dimension are given in the following table:
Mass is a derived dimension with units of slug and dened in terms of the primary dimensions as
1 2
slug = 1 lbf s ft ⋅
(1.1)
Converting from the unit of mass to the unit of force is readily accomplished because the slug is dened in terms of the lbf (pound-force).
