# Buoyancy of balloon submerged

1. Oct 13, 2009

### stosw

1. The problem statement, all variables and given/known data

Calculate the balloon lift if it were submerged in water.

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

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

2. Relevant equations

Lift = Volume * gravity * (Pfluid - Pbody)

$$\frac{Pfluid}{Pbody}$$ = $$\frac{Mfluid}{Mbody}$$

The Mfluid is molecular weight of Water.

3. The attempt at a solution

Using:
$$\frac{Pfluid}{Pbody}$$ = $$\frac{Mfluid}{Mbody}$$

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?