Is Our Weight Measured in lbm or lbf?

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Discussion Overview

The discussion centers around the measurement of weight, specifically whether it is expressed in pound-mass (lbm) or pound-force (lbf). Participants explore the implications of weight measurement in different gravitational contexts, such as on Earth versus the Moon, and the terminology used in everyday language versus scientific definitions.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether personal weight is measured in lbm or lbf, noting the difference in weight on the Moon and suggesting that weight should be considered as lbf.
  • Another participant points out that domestic scales measure the force applied to them, implying that they should display results in Newtons, but they are calibrated to show mass in kg, which can lead to inaccuracies in different gravitational fields.
  • A different viewpoint emphasizes the variability of weight as a force that depends on location, suggesting that the common usage of the term 'Weight' can lead to confusion without clear context.
  • One participant clarifies that weight is measured in pound-force and mass in pounds or pound-mass, while also noting the ambiguity of the term "weigh" in everyday language.
  • A light-hearted comment is made about the topic being "weighty," indicating the complexity and ongoing nature of the discussion.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and measurements of weight and mass, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants highlight the dependence on gravitational context for weight measurements and the potential for confusion arising from the use of everyday language versus scientific terminology.

txdw16
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I'm sure this has been asked before but it's annoying me. When we weigh ourselves is it in lbm or lbf?

Because we weigh different on say, the moon, our weight must be lbf right? But if I weigh 150 any unit converter will say I weigh 68kg. Or do I weigh 2.13kg? Can I say I weigh 21 Newtons?
\frac{150lbf}{32ft/s^2}*\frac{1lbm}{2.2kg}\cong2.13kg*9.8m/s^2\cong21N
 
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Domestic scales measure the force you apply to them so it would be reasonable for them to display the result in Newtons but they all assume they will be used on Earth and have scales calibrated in kg (or some imperial equivalent). In effect they attempt to display your mass. Since gravity isn't the same everywhere on Earth they won't display the correct mass everywhere.
 
This is an old chestnut. Essentially, Weight is the force which pulls you down and it can vary with position. One really has to come to terms with the common usage of the term 'Weight' and use the context of any statement to decide what is really meant. You can waste far too much time trying to reconcile the two worlds of Science and everyday life. There is a danger of getting a name for nerdiness if you inflict strict definitions on innocent people in civvy street.
 
Weight is measured in pound-force. Mass is measured in pounds, (or pound mass?). But the term "weigh" can mean many things in the English language, including general measurement. Example: "weigh a decision"
 
This certainly is a weighty subject.
 

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