Force in the SI and the American Engr. Systems

Weight
Note: Weight is a force, therefore:

In the American Engineering System, force is considered a fundamental dimension and the unit for it is the pound-force (lbf).

1 lbm exerts 1 lbf under the average gravitational acceleration of 32.174 ft/s2.

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gc is the

Standard Gravitational Constant

Always write the subscripts on lbm and lbf !

Newton's Second Law

In the SI System, force is not a fundamental dimension. The units of force are Newtons and 1 kg exerts 1 N of force under an acceleration of 1 m/s.
Therefore:
Definition of a Newton
Standard Gravitational Constant, SI
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Ch 1, Lesson B, Page 5 - Force in the SI and the American Engr. Systems