How much helium does it take to float a man?
550091
Depends on local airpressure and weight of the man.\nAt 1013 millibar (= 1 atm) the mass of 1m³ of air is 1.29 kg\nand the mass of 1 m³ of helium is 0.178 kg\n\nTo make a mass of 75 kg weightless you'll need 75/(1.29-0.178) = 67 m³ of helium, to lift it a little bit more.
881994
An balloon has positive buoyancy (floats) if the volume of air it displaces weighs more than the balloon. This is the same as saying the balloon is less dense than the air it is in.\n\nIn air, which is mostly nitrogen and only about twenty percent oxygen, a balloon will not float if its overall density is greater than air. That is, if the balloon and the gas it contains weighs more than the volume of air that it occupies the balloon will sink. So you can't fill the ball on with air and expect it to float because the balloon fabric is denser than air.\n\nHowever, there are three (and only three) gases whose densities are less than air: hydrogen, helium, and hot air. If the volume of the balloon is large enough, the weight of the hydrogen or helium or hot air when added to the weight of the fabric will be less than the weight of the air the balloon displaces. The balloon rises.\n\nAll of this is commonly referred to as manifestations of Archimedes' Principle.
184965
The density of the human body is very near the density of water.  Personally, I float when my lungs are full and I sink when I exhale.  I think that water's density of 1000 kg/m3 is a good estimate of my density.\n\nI weigh about 75 kg (take your weight in pounds divided by 2.2)\n\nSo this means my volume is 75kg/(1000kg/m3) = 0.075 cubic meters.
530899
Helium has two electrons, so it's first shell is full.
102929
Density is the mass per volume.  Buoyancy is the comparison of an object's density with the density of the surroundings.  Helium balloons rise being lifted by the surrounding air sinking around them.  They are less dense than the air they displace, hense are buoyant.
1236
Take a deep breath.  The average density of a human is 61-67lbs/ cubic foot, but this drops to 56-62 lbs/cu foot if you inhale.
487947
Helium is a gas that is ONLY found trapped inside rocks ( on Earth ).\n\nThis is because Helium is so light that it will escaped into SPACE when released.  ( Helium is not found in the air )\n\nYour helium balloon will explode before it stops rising.\n\nIf the balloon doesnt explode ( for example only ) , then it will rise into space and stabilize in a orbit at an equilibrium point where the gravitational attraction of the Earth to the substance of the balloon matches the lift of the balloon ( the tendency of Helium to escape ).\n\nI dont know where this point would be but i dont think its necessary to understand your question.
712651
Mostly hydrogen, some helium, and relatively small amounts of various other elements.
108625
I guess the helium ballon will lift the same mass, not more. \nThis is because although the mass will weight less (1/6), also the ballon will have less lift force because this depends on the volume x density x g(moon), and g(moon) is 1/6 also, so the less weight counteracts with less lift force.
946246
Helium particles are very small, in fact they are the smallest free particles that normally exist in nature. Although the plastic your balloon is made out of can stop water and sand and marbles and various other materials that have large particles, helium is small enough to go through, so it leaks.\n\nNow, there are certain kinds of balloons which are made out of special plastics and leak hardly any helium at all. However they are more expensive than the standard, cheap, leaky ones.
706335
The density of helium is only one-seventh of the density of air at the same pressure, so when the balloon is stable, the other six-sevenths has to be accounted for by a combination of (i) the weight of the balloon fabric, and (ii) the tension in the balloon fabric keeping the helium at a higher pressure than the surrounding air.  There is no simple answer, but four miles would not surprise me.
443013
It depends on how far out of the water you wish to be.  Humans are very close to being bouyant-we are more dense than water, but have lungs full of air, thus a lean man with a large lung capacity is bouyant with a deep breath.  Its isnt the pounds of air that matter, its the pounds of water displaced by the air.  If you hold onto a 10 gallon jug full of air, it displaces 10 gallons worth of water, which is about 80 pds-well more than you need to keep your upper body above water.  For a 200 pd man, he would need an water-displacing container of 25 gallons (this could be a boat or anything else that displaces water for air).
62040
Two.  "Normal helium has 2 protons and 2 neutrons in its nucleus, giving it an atomic weight of 4."
56848
0.025gHe=1molHe---6.02e23\n--------=4gHe-----1molHe\n\n4 grams of He=1 Mol of He. 1 Mol of He=6.02e23 atoms.\nSo that all equals 3.7625e21
83455
Jupiter is about 90% hydrogen and 10% helium (by numbers of atoms, 75/25% by mass)
1000320
Helium, CO2, Hydrogen and various others.
835571
Balloons filled with air will last for days to weeks, and can be filled the day before your function. Balloons filled with helium gas usually last less than a day, and need to be inflated on the day of your function. If you are DIY, always do a test inflation the day before to determine the flying time of the balloons under your conditions. Flying times will depend on the size and quality of the balloons, and the conditions on the day you inflate them. A standard size helium balloon is 28cm (11") and should fly for 12-18 hours. Balloons are adversely affected by heat, wind and sun, so keep them in a cool, dark place until needed. Australia is a hot country, so I am always conservative with balloon flying times, and any extra is a bonus. Don’t leave helium filled balloons in your car while you shop for the party – pay the extra for delivery or DIY at the venue just before the function. (1)\n\n\nMathematically, it depends on several variables m = PVM/RT where: m = mass of the gas in grams P = pressure inside the balloon, in atmospheres V = volume in liters M = Molecular weight of the gas R = a constant = 0.082 T = Absolute temperature, Kelvin At sea-level, the air pressure is 1 atmosphere and say we are at room temperature. Then P = 1 and T = 293K.'\n\nAlso, remember that you should never release helium ballons into the air. Balloons cause the death for countless numbers of sea turtles and whales. Balloons cause them to suffocate or starve to death (by blocking stomach or air valves). Also metallic balloons can cause power outages when they get caught in power lines. (2)