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Primary dimension

  1. Sep 5, 2009 #1
    1. The problem statement, all variables and given/known data
    For each quantity listed, indicate dimensions using mass as a primary dimension and give typical SI and English units:
    power
    pressure
    modulus of elasticity
    angular velocity


    2. Relevant equations



    3. The attempt at a solution
    im not sure i understand what it is asking for. There is another question asking the same thing but with "force" as primary dimension.
    with mass being primary dimension, i guess it is referring to MLtT, but that is considered SI units isnt it? so wouldnt i just give examples of SI units? i dont see where english units come in, im confused

    an example of Power in SI is 1 watt = 1 J/s. would that be the correct answer for that part? im sure this question is easy but im not clear on what they are asking for
     
  2. jcsd
  3. Sep 6, 2009 #2

    tiny-tim

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    Hi jaredmt! :smile:

    I think they're asking for something like ML2/T3 (i made that up! :rolleyes:), watt (that's SI), and foot-pound-horsey-thingy (that's English, or imperial). :wink:
     
  4. Sep 6, 2009 #3

    Redbelly98

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    I agree with tiny-tim. So Force would be ML/T2 in this problem, but would simply be F when force (not mass) is a primary dimension.

    Don't worry about whether length L is in meters or feet, that isn't relevant here.
     
  5. Sep 6, 2009 #4

    nvn

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    I agree with Redbelly98, except T should be lowercase t.
     
  6. Sep 6, 2009 #5

    Redbelly98

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    Typically in problems like this, when one is expressing time units, an uppercase T is used. Just as uppercase M and L are used for mass and length units.

    A lowercase t is used to express time as a variable in equations, but that is not what is being done here.
     
  7. Sep 6, 2009 #6

    tiny-tim

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    I agree with Redbelly98 :biggrin:
     
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