1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Measuring Force!

  1. Oct 10, 2008 #1
    Can you measure a force?
  2. jcsd
  3. Oct 10, 2008 #2

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    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.
  4. Oct 10, 2008 #3
    yes... what do you think a weighing machine reads?
  5. Oct 10, 2008 #4


    User Avatar
    Science Advisor

    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.
  6. Oct 10, 2008 #5
    what force do you think causes the pressure-or-whatever u say?

  7. Oct 10, 2008 #6


    User Avatar
    Science Advisor

    Don't forget about mass!

  8. Oct 10, 2008 #7


    User Avatar

    Staff: Mentor

    Question asked and answered. Thread locked.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook