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Dimensional Analysis Equation Help

  1. Jan 27, 2009 #1
    1. The problem statement, all variables and given/known data

    The question states which of the following equations are dimensionally correct?
    (a) v^2=v^2+2at or (b) v^2=v^2+2ax

    2. Relevant equations
    v=[L]/[T], x=[L], a=[L]/[T]^2


    3. The attempt at a solution
    (a) v^2=v^2+2at
    [L]^2/[T]^2=[L]^2/[T]^2+([L]/[T]^2)([T])
    [L]^2/[T]^2=[L]^2/[T]^2 + [L]/[T]

    (b)v^2=v^2+2ax
    [L]^2/[T]^2=[L]^2/[T]^2+([L]/[T]^2)([L])

    The correct answer listed is b.. I just dont understand why a is incorrect while b is correct.
    Can someone please explain? Thanks!
     
  2. jcsd
  3. Jan 27, 2009 #2
    (a) v2=v2+2at
    [L]2/[T]2=[L]2/[T]2 + [L]/[T]

    The last term [L]/[T] is not squared like the other two.

    (b)v2=v2+2ax

    [L]2/[T]2=[L]2/[T]2+([L]/[T]2)([L])

    The last term

    ([L]/[T]2)([L])=([L]2/[T]2)

    and this is of the same dimensions as the other two terms.
     
  4. Jan 27, 2009 #3
    So Simple!! Thank you so much.
     
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