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# Difference Between Lbf and Lbs

Lbf vs Lbs

Pound mass lbm and pound force lbf are two units in the imperial system of units. They are related to each other and often times confused. Even though it is not a consistent system of units, having many drawbacks, imperial system of units or feet-pound-second system of units are still used.

lbs or lbm (Pound)

Pound is the unit of mass in the imperial system (or f.p.s) system of units and equal to 0.45359237 kilograms. The unit is derived from the Roman system of units. There have been many variations about the exact mass of a pound, but the Avoirdupois pound is considered as the legal standard in the modern world. It is one of the basic units of the feet-pound-second system.

The pound is 16 ounces, and 1 slug is 32.17405 lbm pound mass.

lbf (Pound Force)

Pound force (lbf) is the unit of force in the imperial systems of units. It is defined as the force needed to accelerate a 1 slug mass (or 32.17405 lbm) at the rate of 1 ft/s. This can be mathematically expressed as follows;

1 lb= 1 slug × 1 ft/s = 32.17405 lbm × 1 ft/s

The relation, in general, is the Newton’s second law. In order to counter the inconsistency, a conversion factor is added to the general equation of the Newton’s second law.

pound force=C ×pound mass×acceleration

Where 1/(32.17405 ) converts the pound mass into slugs within the equation. The pound force is used in derived units such as pound feet, which is the unit of work in the f.p.s system.

What is the difference between Lbf and Lbs?

• Lbs or lbm (Pound) is a unit of mass while Lbf (pound force) is a unit of force in the imperial system of units.

• Pound force is the force needed to accelerate a 1 slug mass (32.17405 lbm) at the rate of 1 ft/s.

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