Dots on physics equations. What do they mean?

  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?
  2. jcsd
  3. mfb

    Staff: Mentor

    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. ZapperZ

    ZapperZ 30,744
    Staff Emeritus
    Science Advisor
    Education Advisor

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

  5. 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. Nugatory

    Staff: Mentor

    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. 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. This is what I am talking about.

    Attached Files:

  9. mfb

    Staff: Mentor

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

    Staff: Mentor

    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. This is the entire equation

    Attached Files:

  13. mfb

    Staff: Mentor

    That is a punctuation mark.
  14. Thank you good sir.
  15. it's just derivative wrt time

    x = dx/dt
    = lim: t→0 in x/t
  16. CompuChip

    CompuChip 4,296
    Science Advisor
    Homework Helper

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

    x =

    second derivative

    eg if
    x=t8 e(t2)

    a =


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


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

    Staff: Mentor

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

    Staff: Mentor

    Over means over, thread closed.
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