Does a vacuum react the same as helium does to air?

Question

by an estimate a liter of air weighs 1.25 grams, and a liter of helium is 0.18. So basically anything under a gram of weight will float. So thats to say if you were to put a vacuum in a liter bottle it would float even better since a vacuum has zero grams of weight. But what I am most curious about is if you put a vacuum in a bottle and a helium in another bottle wouldnt the vacuum bottle collapse? And why is it that the helium bottle wont? The range between 0.18 and 0.00 is not much so why such an extreme difference?

Answer 1

Excellent questions!

A vacuum has zero mass, and would indeed "float", the trouble is that the air will simply move to fill in the vacuum, almost instantly destroying it. Now suppose you could create a rigid, nearly weightless container that could resist that pressure of the air. Now you "fill" it with a vacuum. Undoubtably, this would float in air, probobly a good deal more bouyantly than helium.

If I understand your second question correctly, you have two entirely seperate bottles, one with nothing in it (a vaccum), the other with helium in it.

Lets take the helium bottle first. The outside air is pushing on the bottle, exerting a pressure. Likewise, the helium inside is pushing outwards. If the pressures are the same, -regardless of relative weights- the bottle will "feel" no net force. If the pressure inside the bottle is less than the outside pressure, the bottle will "feel" a pressure crushing it. If this pressure is great enough, the bottle will collapse.

Now lets take the vacuum bottle. In this case, the pressure inside is zero. The pressure outside remains the same, but because there is a greater pressure differential across the surface of the bottle, it is more likely to break.

Hope that helped!

Answer 2

the helium is lighter, but still exerting a pressure against the sides keeping it from collapsing. The vacuum has no internal pressure to counteract the pressure of the air on the outside, so it collapses. The weight has no real effect as to the crushing because that deals with the pressures, not the masses.

Answer 3

Most bottles won't break if you evacuate them. But the weight of a bottle us usually enough to keep it from floating, whether evacuated or filled with helium. A balloon has very little weight. But fill it with helium and it will displace heavier air and float. Fill it with a vacuum and nothing happens. It displaces nothing. If your bottle was weightless, it would float better when evacuated than when filled with helium, but would float in both cases.

Answer 4

because helium is just that little bit lighter

Answer 5

Have you considered pressure?