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Homework Help: Dimensionally corect equation ?

  1. Sep 10, 2008 #1
    1. The problem statement, all variables and given/known data

    -------------Dimension------------------...
    distance (x) (L) Acceleration (a) (L)/(T)^2

    Time (t)-----> (T) Force (F)-----> (M)(L)/(T)^2

    Mass (m)----> (M) Energy (E)-----> (M)(L)^2/(T)^2

    Speed (v)-----> (L)/(T)
    Is the following equation dimensionally correct?
    A) X= 1/2 at^3

    2. Relevant equations



    3. The attempt at a solution

    A) X= 1/2 at^3
    [L] = 1/2 [L]/[T]^2 * [T]^3

    i know my proff said numbers such as 1/2 don't have dimension but i dont really understand how to solve this....what am i suppsoed 2 do with 1/2
     
  2. jcsd
  3. Sep 10, 2008 #2

    Hootenanny

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    Welcome to PF Star20,

    QUOTE=star20;1867892]

    A) X= 1/2 at^3
    [L] = 1/2 [L]/[T]^2 * [T]^3

    i know my proff said numbers such as 1/2 don't have dimension but i dont really understand how to solve this....what am i suppsoed 2 do with 1/2[/QUOTE]
    Scalar coefficients are irrelevant in dimensional analysis, only the dimensions themselves are important, you can safely ignore the fact of 1/2.
     
  4. Sep 10, 2008 #3

    Dick

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    Drop the (1/2). It doesn't have any dimensions.
     
  5. Sep 10, 2008 #4
    ok thanks
     
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