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Homework Help: F vs. a Graph's Intercept

  1. Oct 7, 2006 #1
    My question concerns the y-intercept of the force vs. acceleration graph. When I plotted my data, the regression line had an intercept that was not 0. What does this signify? I know that the intercept is the amount of force when the acceleration is 0 m/s^2. Shouldn't it be 0 N at 0 m/s^2? Does this mean there was a source of force that I neglected to take account for while recording the values for the graph?

    Thanks.
     
  2. jcsd
  3. Oct 7, 2006 #2

    arildno

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    Most likely!
    Force is strictly proportional to acceleration.
     
  4. Oct 7, 2006 #3

    Integral

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    Just how non-zero is it? Could it be an indication of measurement errors?
     
  5. Oct 8, 2006 #4

    andrevdh

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    Consider the case if the graph was drawn a vs F.

    The x-intercept will indicate that some non-zero force was necessary to start the acceleration of the object - a tipical real life situation we find in order to overcome the ever present frictional forces.
     
  6. Oct 8, 2006 #5
    The intercept was about 0.0051 (N).
     
  7. Oct 8, 2006 #6

    arildno

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    What are the typical magnitude of your data values?
     
  8. Oct 8, 2006 #7
    Which values? The a values or the F values?

    All the force and acceleration values are less than 1.0 N and 1.0 m/s^2, respectively.

    My smallest F value is 0.0961 N and greatest is 0.446 N.

    My smallest a value is 0.188 m/s^2 and greatest is 0.869 m/s^2. The smallest F value corresponds with my smallest a value, and the greatest F value corresponds with my greatest a value.
     
  9. Oct 8, 2006 #8
    A frictionless setup was organized (or was attempted to be organized), but it is possible to still have frictional forces as a source of error?
     
  10. Oct 8, 2006 #9

    arildno

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    Indeed there can, and will be!
    In your case, the force discrepancy is about a twentieth of your least value, that is most likely the effect of friction showing up.
     
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