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Help with simple dimensional analysis question

  1. Sep 13, 2009 #1
    Which one of the quantities below has dimensions equal to ML/T2

    a) mv
    b) mv2
    c) mv2/r
    d) mrv
    e) mrv2/r2

    I tried splitting it up in M*(L/T)*1/T
    which would lead me to mv*T-1 and then I get stuck

    Please help!
     
  2. jcsd
  3. Sep 13, 2009 #2

    Redbelly98

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    Welcome to Physics Forums :smile:

    Since it's multiple choice, how about examining each answer and seeing if it matches ML/T2

    For example:

    a) mv = M L/T (is not ML/T2)
    etc.
     
  4. Sep 13, 2009 #3
    I'm working on it, but what is the r in the answers? Also, why does the m become a capital M?
     
  5. Sep 13, 2009 #4

    Redbelly98

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    For dimensional analysis problems, it's customary to use capital letter M, L and T for Mass, Length, and Time.

    r is a distance or length.
     
  6. Sep 13, 2009 #5
    Ok, I think I figured it out...

    I took mv2/r

    (M(L/T)(L/T))/r

    I assumed r = L since both are length measures so...

    (M(LL/TT))/L

    (M(LL/TTL)

    M(L/TT)

    M(L/T2)

    I don't know if I should be equating r to L though...
     
  7. Sep 13, 2009 #6

    Redbelly98

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    That's correct. Yes, r has dimensions of Length, so use L for its dimension.
     
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