Pound-force (lbf)

Definition

Pound-force (lbf) is a unit of force in the Imperial and U.S. customary systems. It is defined as the force exerted by gravity on a mass of one pound at standard gravity (9.80665 m/s²). Thus, 1 lbf = 4.44822 N.

History

The concept of pound-force emerged in the 19th century as engineers and scientists required a consistent unit of force. The Imperial system formalized it, aligning with the use of pounds as a unit of mass. The establishment of the gravitational constant in the late 19th century further solidified its application.

Uses

Pound-force is widely used in engineering, especially in the United States, for measuring forces in mechanical and civil engineering. It is also common in automotive specifications and aerospace applications.

Conversions

  • 1 lbf = 4.44822 N (exact)
  • 1 lbf = 0.45359237 kg·m/s² (exact)
  • 1 lbf = 0.224809 lb·ft/s² (exact)

Fun Facts

  • A common misconception is that pound-force and pound-mass are interchangeable; they are not.
  • The pound-force is often used in tire pressure measurements in the U.S., highlighting its practical application in everyday life.
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