What volume of helium, at sea level pressure, and at 60 degrees F,
would lift one pound of weight?

---

Clarification of Question by comogreg-ga on 08 Aug 2004 09:58 PDT

what volume of helium, at sea level pressure, and at 60 degrees F,
would lift one pound of weight to a thousand feet?

---

Request for Question Clarification by omnivorous-ga on 09 Aug 2004 07:15 PDT

60 degrees at sea level or at 1,000'?  Are we to assume normal
adiabatic lapse rate?
http://www.campusprogram.com/reference/en/wikipedia/d/dr/dry_adiabatic_lapse_rate.html

Best regards,

Omnivorous-GA

According to another Google Answer, about 15.886524 cubic feet.
http://answers.google.com/answers/threadview?id=17938
Not certain how much of a role temperature plays, considering it's
pretty much all about displacement and gravity.

(Read: Nobody really considers the temperature of the water when
asking how much water the ship displaces)

Neither do I believe distance much matters. Consider nobody asks how
much lead has to weigh to sink 1000 feet in water. And yes, they are
the same concept.

Let me rethink that. It does make a difference, doesn't it? The
equivalence is lead pulling a balloon underwater 1000 feet, but again,
not really. As you go down, pressure increases around the balloon.
Eventually, the pressure should either equivalently buoy the balloon,
or the pressure would pop the balloon.

Pressure decreases about the helium balloon. I know I've given part of
the answer, but I wonder if the other part is that helium escapes the
balloon as the balloon expands. Still, I doubt that there is a
correlation in volume versus height, unless it's a functional issue
with the balloon.

Height absolutely makes a difference, because as you increase height
above sea level, atmospheric pressure decreases.  Therefore, the
number of air molecules physically present decreases.  Therefore, the
air density decreases.  (Same reason why it's harder to breathe atop
Mt Everst than in Hawaii -- there's less air!)

Since the whole reason helium lifts has to do with buoyancy force
caused by varying densities, then as the delta-density decreases to
zero, lifting power also decreases to zero.

Assuming your two gases (air and helium) are at the same temperature,
the effects of temperature are cancelled out.   You can use the
equation PV = nRT, where P is your pressure, V = volume, n = number of
moles of gas, R = universal gas constant, T = temperature in Kelvin.