How many helium balloons would it take to lift a 15 stone person?

Question

Just the standers latex balloons, nothing fancy.

Answer 1

Lessee, a stone is about 6.36 kg, right? Times 15 equals about 95kg. At sea level, air weighs 1.2kg per cubic meter, but a helium balloon only weighs about 1/5 of that, so a cubic meter of helium will lift about 1kg.

Let's say a standard latex balloon is about 1/4 of a meter in diameter. Then its volume is

4*pi*r^2/3 =

4 * 3.14 * 0.125 * 0.125 / 3 = 0.065 cubic meters, so it takes about 15 of them to lift 1kg, times 95 equals 1425.

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Answer 2

What's the volume of a 'standard' latex balloon? I've seen them in all sizes from a few inches to over a foot.
All you have to do is calculate the displacement of the balloon, then calculate the difference in mass for that volume of air and that volume of helium, and that's the bouyancy for that baloon. However many of those it takes to add up to 15 stone is your answer. (Note for the 'purists': Yes, the helium is under pressure so the mass of gas will be slightly higher than the calculation shows. But it'll only be only off by 1 or 2 percent. If you calculate 60 balloons, add a couple more just to be sure ☺)

Doug

Answer 3

not really sure but go to discovery.com and find the mythbusters website and go there they actually lifted a young girl with helium balloons. they calculated it in pounds though so you would have to convert it to find out.