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DBCOOPER

Helium

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UNFORTUNATELY that calculation is incorrect because it uses the atomic masses of N and O instead of the molecular masses of N2 and O2 to calculate the mass of 1 mole of air!

This leads to a very large error in the result.
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The only sure way to survive a canopy collision is not to have one.

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I -think- that was just in the explanation section. The actual calculation at the bottom of the page seemed like it worked to me.

Maybe I missed something.




Apparently.

MM of Helium = 4
MM of air (average) = 28.8

Therefore any given volume of He has approx 1/7 the mass as the same volume of air. According to Archimedes, the boyancy is the difference in masses, which is then 6/7 the mass of the air.

To save PV=nRT we'll use a standard atmosphere:

Density at sea level = 1.23kg/m^3
So 1 m^3 of He will lift approx 6/7 * 1.23kg. which is real close to 1kg.

Which is quite different from the answer on the site you quoted.

Edited to add trivia:

How much more lift would you get from hydrogen? Not much even though a He atom weighs 4x as much as an H atom!

MM of H2 molecule = 2, while air is approx. 28 (see above)

Therefore the additional lift of H2 balloon compared to He balloon = 1/14 * 1.23kg which is less than 9% increase. Add in the Hindenberg factor, and you can see why He is more popular.
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The only sure way to survive a canopy collision is not to have one.

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Kallend-
I can't believe your brain doesn't explode from all that stuff you have in there. ;)



What makes you think it hasn't?:o

Actually it's easy. The secret is that I don't watch TV so there's less junk in there:)
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The only sure way to survive a canopy collision is not to have one.

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