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Units for pressure in a cylinder

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  1. Jun 9, 2015 #1
    I am calculating pressure on a spherical cylinder of 10 mm diameter by wind tunnel. when measuring values in manometer filled with water which density is 1000 kg/m^3 so by hydro-static formula the pressure difference is [P2-P1=ρg(h2-h1)]

    so by this formula the ρ unit is in kg/m3 and gravity(g) we know 9.81 m/s^2 so the unit of (h2-h1) must be meter? or mm will be fine as well?
    I am confused by this small problem..

    <<Mentor note: Removed comments unrelated to question>>
     
    Last edited by a moderator: Jun 9, 2015
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  3. Jun 9, 2015 #2

    Orodruin

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    The formula does not presuppose anything about the units. You will get the same units out as you put in.
     
  4. Jun 9, 2015 #3
    Thank you...

    But the unit which i put in must be same...for instance if i have ρ in meter and g in meter as well...so can i use h means the height in mm?
    or it should be meter too?

    that's my real question.
     
  5. Jun 9, 2015 #4

    Orodruin

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    You can use h in mm, but it will make your result have units of N mm/m^3 instead of N/m^2. (The first is equivalent to units of mPa.)
     
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