1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted

Similar Threads - Buoyancy balloon submerged Date
Physics of a Hot Air Balloon Jan 12, 2017
Buoyancy and helium balloons Apr 9, 2015
Moles of gas helium balloon; buoyancy; PV=nRT Jan 22, 2015
FBD of Hot Air Balloon and Buoyancy May 12, 2013
Hot Air Balloon and Buoyancy Feb 13, 2013