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Buoyancy of balloon submerged

  • Thread starter stosw
  • Start date
  • #1
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Homework Statement



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

Homework Equations



Lift = Volume * gravity * (Pfluid - Pbody)

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

The Mfluid is molecular weight of Water.

The Attempt at a Solution



Using:
[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?
 

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