You are asked to add ballast to a helium-filled ballon until it will float in the centre of the room?
958394
You could tie a long string or ribbon on it and let it go.  At some point, the balloon will stop rising.  Cut the string just where it touches the floor.  Neutral bouyancy achieved!
937535
The helium is compressed when it is in the tank.  When it exits the tank, it expands in the balloons until it equalizes with atmospheric pressure.  Any gas can be compressed, as to occupy a smaller volume.  You can see this if you would take a plastic container fill it with air, and submerge it to the bottom of a swimming pool.  you would able to see that the container would deform because of the volume change of the container.
372306
Depends on how much helium you put into it, and how big your baloon is, and how and where you release it, and... it may well heep going up and up and up to the top of our atmosphere if you put enough in.
86061
Flipping over wouldn't be a problem; the asker is building a magnetic monopole on the ping-pong ball.  \nIs this possible?  Check the ref.website and find "Monopole Attempt".  They say that the other pole would leak out through the spaces between the magnets.  \nSomewhere I heard there's only room for one monopole in the universe.  \nWould the first person to do it be a monopolist?
24312
Depends on temp and pressure, but at room temp, avg. pressure, helium's a gas
686605
Helium is lighter than air and cause the ball to float away.\n\nCarbon Dioxide is heavier than air so the ball would not bounce so well and it would be harder to kick.\n\nOxygen is lighter than air, but the difference is so small you wouldn't notice, no more that a ball being slightly over/under inflated.\n\nSince air is the cheapest, at a cost of nil, I suggest you put that in you balls.
941032
waterballoons, not only can you have more fun with them but they cant harm you. Once when i used a helium balloon, my voice was like that for half an hour!! it freaked me out! Waterballoons are simply fun.
215329
You need a green- helium safe type- laser, a converter, an adapter. \nThe company heathkit/zenith used to sell them.\n \nAnd you need a lot of money to buy the equipment.
1151517
50percent of ice should be added to the room
896989
You can make a ball bearing launcher:\nhttp://my.execpc.com/~rhoadley/maglnch.htm\n\nYou can make your own levitating MagLev train:\nhttp://my.execpc.com/~rhoadley/magtrain.htm\n\nOther info is available here:\nhttp://www.kn.sbc.com/wired/fil/pages/listmagnetsan1.html
979598
No. Combustion occurs b/c something reacts with oxygen. So unless the helium is contaminated with oxygen, no combustion can take place.
140469
The helium balloon will continue to travel forward until it collides with the right side of the van that is now moving towards the balloon.  Once the side of the van and the balloon meet, the balloon will travel to the left.\n\nFrom the perspective of someone in the van, the balloon will APPEAR to move to the right.
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)
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.
1161718
Next time use Helium to inflate her then walk towards an open window  let her out and wave good bye lol
96152
if i am visualizing correctly what you want ,i suspect you will have to build it.aren't you going to waste a lot of space?
450269
Well if the ball is hollow then it will float. If the weight of the water displaced is greater than the weight of the object then it will float because the object is lighter then the area of water it is taking up.