how many sq. feet of helium are required to lift one pound?

Question

of course i meant cubic

Answer 1

The density of helium is 0.1786 g/L, and the density of air is 1.2 kg/m^3. With proper unit conversion, the density difference is 0.064lb/ft^3. Therefore it takes 15.7 ft^3 of helium to lift one pound.

Answer 2

You want a 'cubic feet' answer. Not square foot. I'm sure you can figure it out mathmatically - I was a weatherman in the Air Force and we used to launch weather balloons with about a pound of sensing electronics (temperature, barometric pressure, height, etc) and the balloon we used would just about fill your livingroom. Also, by the time it reached the upper levels, sometimes 5 millibars or even less, the balloon would be stretched to about a mile across.