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Dots on physics equations. What do they mean?

  1. Aug 25, 2013 #1
    So when there is a dot above the equation it means with respect to time. What does it mean if there are two on the top or one on the side?
     
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  3. Aug 25, 2013 #2

    mfb

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    Two on top of a variable usually mean the second derivative with respect to time.
    "One on the side" - can you give an example?
     
  4. Aug 25, 2013 #3

    ZapperZ

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    For future reference, always provide context and sources when you ask something like this.

    Zz.
     
  5. Aug 25, 2013 #4
    That is a shorthand of writing the derivative. Two dots above would mean double derivative.

    One on the side - I don't recall that one.

    PS. 0405, 0406, 0408 and they all showed up with my post not before
     
  6. Aug 25, 2013 #5

    Nugatory

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    One dot on top usually means the first derivative with respect to time (that is, speed), two dots on top the second derivative with respect to time (that is, acceleration).

    A dot on the side? Show us an example of what you mean and you'll get a better answer.
     
  7. Aug 25, 2013 #6
    perhaps the dot on the side - he is refering to f prime and f double prime - only thing i can think of, only it's not a dot.
     
  8. Aug 25, 2013 #7
    This is what I am talking about.
     

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  9. Aug 25, 2013 #8

    mfb

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    I think that is a punctuation mark. Or a misplaced time-derivative point.
     
  10. Aug 25, 2013 #9
    Well it so the Euler Lagrange equation. Is it suppose to be there ?
     
  11. Aug 25, 2013 #10

    mfb

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    That's hard to tell from the RHS only, as both derivatives (with and without dot) are interesting.
    You can check the units to find it out.
     
  12. Aug 25, 2013 #11
    This is the entire equation
     

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  13. Aug 25, 2013 #12

    mfb

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    That is a punctuation mark.
     
  14. Aug 25, 2013 #13
    Thank you good sir.
     
  15. Aug 30, 2013 #14
    it's just derivative wrt time


    .
    x = dx/dt
    = lim: t→0 in x/t
     
  16. Aug 30, 2013 #15

    CompuChip

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    namanjain, OP is talking about the second dot.
    That's just a period marking the end of the sentence.
     
  17. Aug 31, 2013 #16
    ohh! sorry read half of the first sentence
    well 2 on top means:


    ..
    x =
    d2x
    ______________
    dt2

    second derivative




    eg if
    x=t8 e(t2)

    a =


    d2x
    ______________
    dt2

    get answer using wits,(:tongue: it's short)

    aNs

    a= 56t6e(t2) + 34t8e(t2) 4t10e(t2)
     
    Last edited: Aug 31, 2013
  18. Aug 31, 2013 #17

    mfb

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    namanjain please read the full thread, you are not adding anything new here.
     
  19. Sep 2, 2013 #18
    then i suppose discussion is over, thank you
     
  20. Sep 2, 2013 #19

    Borek

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    Over means over, thread closed.
     
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