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Buoyancy of balloon submerged

  1. Oct 13, 2009 #1
    1. The problem statement, all variables and given/known data

    Calculate the balloon lift if it were submerged in water.

    Volume of balloon (sphere) = [tex]\frac{(5^3)*(pi)}{6}[/tex] = 125pi/6

    The balloon is filled with hellium.
    Pfluid (water) = 64.2 lb/ft^3

    2. Relevant equations

    Lift = Volume * gravity * (Pfluid - Pbody)

    [tex]\frac{Pfluid}{Pbody}[/tex] = [tex]\frac{Mfluid}{Mbody}[/tex]

    The Mfluid is molecular weight of Water.

    3. The attempt at a solution

    [tex]\frac{Pfluid}{Pbody}[/tex] = [tex]\frac{Mfluid}{Mbody}[/tex]

    Pbody = 14.3 lb/ft^3

    Lift = Volume * gravity * (Pfluid - Pbody)
    Lift = (125pi/6)ft^3 * (32.71) ft/s^2 * (62.4 lb/ft^3 - 14.3 lb/ft^3)
    Lift = 102,925 ft/s^2

    That number seems way too large to me. Could someone shed some light to what it is I did incorrectly?
  2. jcsd
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