Why don't we measure our weight in Newtons?

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Discussion Overview

The discussion revolves around the measurement of weight and mass, specifically why weight is often expressed in kilograms rather than Newtons. Participants explore the implications of using different units in various contexts, including scientific and everyday scenarios.

Discussion Character

  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that weight should be measured in Newtons and mass in kilograms or grams, highlighting a distinction between the two concepts.
  • Others propose that using grams for weight can be more practical in certain contexts, such as in chemistry labs where local gravitational variations do not affect mass measurements.
  • One participant suggests that weighing equipment is typically calibrated to show kilograms instead of Newtons, indicating a preference for mass over weight in common usage.
  • Another viewpoint notes that for most people living near sea level, the distinction between weight and mass can be treated as a simple unit change, suggesting that precision is less critical in everyday situations.
  • Some participants express frustration with the inconsistency in how weight is reported, reiterating that it should ideally be in Newtons.
  • There is a suggestion that in practical settings, such as doctor's offices, individuals might consider providing their mass instead of weight.

Areas of Agreement / Disagreement

Participants generally express disagreement regarding the appropriate units for measuring weight and mass, with multiple competing views on the practicality and implications of using different measurements.

Contextual Notes

Some discussions highlight the dependence on local gravitational variations and the calibration of weighing equipment, which may affect the accuracy and relevance of measurements in different contexts.

Jacinta
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aren't you supposed to measure weight in Newtons? And mass in kilograms/grams?
 
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In some ways, it is probably more scientific to give the weight (mass) in "grams". When a balance type scale is used for very accurate mass measurements, like in a chemistry lab, the local value of the gravitation ## g ##, which can differ slightly depending on the geographical location has no effect on the measured result. ## \\ ## Editing: Meanwhile, a spring balance measures force=pounds. In M.K.S. , a spring balance should read Newtons, but if used as a "weight" scale, it's likely to read kilograms.
 
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I think it's because we measure our weight, typically with a spring, but we really want to know our mass.
So the weighing equipment has been calibrated locally to show kilograms instead of Newtons.
It could show Newtons as well with a second scale, but generally that is left out. ;)
If we bring the same equipment elsewhere, it will have to be recalibrated.
The equipment that @Charles Link mentions measures indeed mass instead of weight, so it doesn't have to be recalibrated when moving elsewhere.
 
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Jacinta said:
aren't you supposed to measure weight in Newtons? And mass in kilograms/grams?
Next time you are asked, at a doctor's office or elsewhere, for your weight, you should definitely give it in Newtons.
 
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As long as you don't stray far from sea level and don't spend much time in free-fall, you can live with not making a clear distinction between weight and mass. You can treat it as a unit change, really.

Since most people live within a few hundred metres of sea level and spend negligible time in free-fall, it's only physicists (who spend a lot of time imagining out-of-the-ordinary situations) who need to be picky about it.
 
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Jacinta said:
aren't you supposed to measure weight in Newtons? And mass in kilograms/grams?

The simple answer is "yes." But when are things ever done as they are supposed to be done?
 
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phinds said:
Next time you are asked, at a doctor's office or elsewhere, for your weight, you should definitely give it in Newtons.

Maybe I should just give them my mass instead.
 
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