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How do I find the instantaneous acceleration for a velocity-time graph that is NOT a

  1. Oct 10, 2011 #1
    http://i52.tinypic.com/95zrsw.png

    ^ okay, if my velocity-time graph looks like that (it was a quick sketch), and I need to find the INSTANTANEOUS velocity at point A and point B, how do I do it?

    I mean, I understand the slope of the tangent = instantaneous acceleration, but this is not a curve. Thus, I also understand to use the normal straight slope. But I don't understand, WHICH slope is the INSTANTANEOUS acceleration for those points?
     
  2. jcsd
  3. Oct 10, 2011 #2

    Ray Vickson

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    Re: How do I find the instantaneous acceleration for a velocity-time graph that is NO

    You read the instantaneous velocities at A and B directly from the graph (because your plot is v vs. t). On the other hand, if you meant to say instantaneous "acceleration" (not velocity), then at A and B there is *no well-defined value*: the acceleration changes instantly from one constant value to another, so the acceleration at one 100 billionth of a second before A is different than the acceleration at one 100 billionth of a second after A.

    RGV
     
  4. Oct 10, 2011 #3
    Re: How do I find the instantaneous acceleration for a velocity-time graph that is NO

    Thank you! Just another simple question, then would it be easier if I make a scatter-plot of my velocity points on my vt graph, then I'll find the line of best fit for average velocity, then find the instantaneous acceleration at the time interval of A and B?
     
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