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I am a furniture design student therefore please keep it simple. a system strong enough to hold the avergae male of say 90 kg is this possible even....

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This is still a challenging problem today, because something would be needed to keep the seat of the chair from drifting laterally. A fixture could be used to hold it in, but any such fixture would be more expensive/impractical than simply having legs on the chair. –  Ataraxia May 21 '13 at 6:52
    
An obligatory ref: en.wikipedia.org/wiki/Baron_Vladimir_Harkonnen –  Deer Hunter May 21 '13 at 7:57
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Some has done this with a bed http://www.dvice.com/archives/2012/05/maglev-bed-lets.php. With the use of the naturally strong rare earth magnets (neodymium magnets). For a chair it would be hard to levitate the chair any reasonable distance, as you would need a decently powerful magnet.

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I'm guessing you're thinking of using disk magnets like these ones. The force between this type of magnet is somewhat complicated to calculate, but at distances larger than the depth of the disk the force falls away as distance squared i.e.:

$$ F \propto \frac{1}{d^2} $$

This means the force falls very rapidly with distance. In the bed that Dan mentioned I'd guess the distance is a few cm, while for a chair the seat would be about 40cm above the floor. That means the force between the chair and the floor would about a hundred times less than the force between the floor and the bed. You'd need either a hundred times as many magnets or magnets a hundred times as strong (the latter isn't physically possible!).

You could certainly have your seat suspended a few cm above some base, like the bed, but I'm guessing you'd like the chair to be apparently floating in mid air. If so I don't think you'll be able to find magnets strong enough.

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