Measuring Force: A Quick Guide

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    Force Measuring
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Discussion Overview

The discussion revolves around the measurement of force, exploring whether it can be measured directly and the devices used for such measurements. Participants engage in a technical examination of the principles behind measuring force, including the roles of various instruments and calibration processes.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that force cannot be measured directly, citing the absence of a "force-o-meter" and emphasizing that measurements rely on known relationships, such as stress-strain.
  • Others argue that weighing machines do provide a reading related to force, although they measure deflection in springs and require calibration.
  • One participant points out that pressure is measured, which is then related to force over a specific area, suggesting a connection between the two concepts.
  • There is a mention that length, time, and possibly charge are the only quantities that can be measured directly, with a later reply adding mass to this list.

Areas of Agreement / Disagreement

Participants express differing views on whether force can be measured directly, with some insisting it cannot and others suggesting that devices like weighing machines do provide force readings. The discussion remains unresolved with competing perspectives on the nature of force measurement.

Contextual Notes

Participants highlight the dependence on calibration and the specific mechanisms of measuring devices, indicating that assumptions about the relationships between measurements and the quantities they represent are crucial to the discussion.

sr_philosophy
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Can you measure a force?
 
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Not directly. There is no such thing as a force-o-meter.

Devices like strain gauges, acclerometers, scales, etc. can be used to measure a force only if they have a known stress-strain relationship.

AFAIK, the only things we can directly measure are length, time, and (maybe) charge. Every other measuring device- thermometers, strain gauges, voltmeters, etc convert the direct measurement into what we 'measure' (pressure, force, voltage...) by a calibration step, that is comparison with a standard.
 
yes... what do you think a weighing machine reads?
 
sr_philosophy said:
yes... what do you think a weighing machine reads?
What? Are you asking or telling? We can not directly measure a force as Andy pointed out. A "weighing machine" as you put it, measures the deflection in a spring. That deflection is calibrated to give a force based on the particular spring constant. Most of the standard types of gauges rely on the measurement of deflection at the core to give you a desired quantity. Even that aside, you never really measure a force, you measure a pressure which is then assumed as the force over a specific area.
 
what force do you think causes the pressure-or-whatever u say?

Pressure...?
 
Andy Resnick said:
AFAIK, the only things we can directly measure are length, time, and (maybe) charge.

Don't forget about mass!

CS
 

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