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Changing a Formula

  1. Sep 29, 2004 #1
    [SOLVED] Changing a Formula

    How do I switch the following formula for time?

    delta d = Vi * delta t + 1/2 * a * delta t^2


    d = distance
    Vi = initial velocity
    a = acceleration
    t = time


    Any sort of steps would be greatly appreciated as I don't just want the answer, I always like to know how it's done :).

    P.S. Sorry about the wording of the question and how the formula is written out, I need to get better at it.
     
  2. jcsd
  3. Sep 29, 2004 #2

    arildno

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    What are the roots of a quadratic equation..?
     
  4. Sep 29, 2004 #3
    Sorry, but I don't really get what you mean (noobness :\). All I can tell you is that I know you solve quadratic equations by factoring.

    EDIT: I removed my nonsense ;)
     
    Last edited by a moderator: Sep 29, 2004
  5. Sep 29, 2004 #4

    arildno

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    You know how to solve for x the following equation, right?:
    ax^2+bx+c=0 (a,b,c constants)
     
  6. Sep 29, 2004 #5

    Looks like you replied while I was editing my post. My answer is yes.
     
  7. Sep 29, 2004 #6

    arildno

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    It seems you have severe problems with simple algebra (your edit is sheer nonsense).
    Now, in order to proceed, try to rewrite your original equation into a form:
    [tex]K_{1}(\delta{t})^{2}+K_{2}(\delta{t})+K_{3}=0[/tex]
    where [tex]K_{1},K_{2},K_{3}[/tex] are constants (identify them!)
    ([tex]\delta{t}[/tex] is "delta t")
     
  8. Sep 29, 2004 #7
    [tex]
    K_{1} = 1/2a, K_{2} = Vf, K_{3} = d
    [/tex]

    Also, wouldn't it be [tex]-K_{3}[/tex], or am I wrong?
     
  9. Sep 30, 2004 #8

    arildno

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    What's wrong with setting:
    [tex]K_{3}=-\delta{d}[/tex]
    Now, you should be able to determine which values [tex]\delta{t}[/tex]
    Choose the root which is makes sense physically.
     
  10. Sep 30, 2004 #9
    I understand now, thanks for helping me out!
     
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