What is the difference between foot pounds and poundals?

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Discussion Overview

The discussion revolves around the differences between foot pounds and poundals, specifically focusing on their definitions and conversion factors. Participants explore the implications of using different units in the context of force and torque measurements.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant, Jason O, inquires about the conversion factor between Newton-meters and foot pounds, expressing confusion over the use of abbreviations like lbf feet and poundal feet.
  • Another participant provides a conversion factor, stating that 1 ft*Lbf equals 1.356 N*m, and emphasizes the importance of distinguishing between pounds force (Lbf) and pounds mass (Lbm).
  • Jason O asks for clarification on the difference between "foot-pound" and "poundal feet."
  • A later reply defines a poundal as a unit of force that causes an acceleration of one foot per second squared on a mass of one pound, noting that it differs from pound-force.
  • The conversion from poundals to Newtons is mentioned as 1 pdl equals 0.1383 N or (1/32.2) Lbf.

Areas of Agreement / Disagreement

Participants express some agreement on the definitions of foot pounds and poundals, but there remains uncertainty regarding the practical implications of using these units and their conversions.

Contextual Notes

The discussion does not resolve the potential confusion surrounding the use of different units and their applications in various contexts.

Who May Find This Useful

This discussion may be useful for individuals interested in unit conversions in physics, engineering, or related fields, particularly those dealing with force and torque measurements.

Jdo300
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Hello All,

This is sort of a dumb question but I'm looking around for the conversion factor between Newton-meters and foot pounds. I looked around at some of the many conversion calculators and some use abbreviations like lbf feet or poundal feet. Which one is actually foot pounds and what's the difference if there is one?

Thanks,
Jason O
 
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1 ft*Lbf = 1.356 N*m

As a note about conversions, if you know the conversions between Lbf to Newtons and feet to meters, then you can simply multiply them to get the conversion you are looking for.

[tex](1 ft-Lb_f)(\frac{1 N}{.225 Lb_f})(\frac{.305 m}{1 ft}) = 1.356 N-m[/tex]

I always use the Lbf notation which indicates pounds force as opposed to Lbm which is pounds mass. Most of the time it never matters between the two. I think it is good practice to make the distinction though.
 
Last edited:
Thanks for the info. Is there a difference between the terms "foot-pound" and "poundal feet"?

Thanks,
Jason O
 
The definition of a poundal is the unit of force equal to the force that produces an acceleration of one foot per second per second on a mass of one pound. It is not the same as a pound-force as above. The conversion is

1 pdl = 0.1383 N = (1/32.2) Lbf
 

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