Thus in the SI system there are distinct names for mass and force which helps alleviate
confusion. When converting between SI and u.s. systems, be alert to the fact that
mass converts from kilograms (kg) to either slugs (sl) or blobs (bl), and force converts
from newtons (N) to pounds (Ib). The gravitational constant (g) in the SI system is approximately
9.81 m/sec2.
The principal system of units used in this textbook will be the U.S. ips system. Most
machine design in the United States is still done in this system. Table 1-4 shows some
of the variables used in this text and their units. The inside front cover contains a table
of conversion factors between the U.S, and SI systems.