Measuring Force: A Quick Guide

[sr_philosophy]

Can you measure a force?

 

[Andy Resnick]

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.

 

[sr_philosophy]

yes... what do you think a weighing machine reads?

 

[FredGarvin]

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.

 

[sr_philosophy]

what force do you think causes the pressure-or-whatever u say?

Pressure...?

 

[stewartcs]

AFAIK, the only things we can directly measure are length, time, and (maybe) charge.

Don't forget about mass!

CS

 

[russ_watters]

Question asked and answered. Thread locked.