If I take a ball made of a solid structure and remove the air, is it possible to make it float? The ball would be rigid, not like a balloon, so that it can withstand the vacuum inside without collapsing.
Air pressure is 15 pounds per square inch - if you reduced this to half that value inside the ball, would that mean it has an upwards force of 7 pounds per square inch, so it would float off the earths surface and into the atmosphere?
2007-01-31 03:10:35 · 9 answers · asked by Michael B 2 in Science & Mathematics ➔ Physics
Well this very question was explored by the early experimenters in lighter-than-air travel. Theoretically, if you could devise a structure that would withstand the air pressure, then yes it would float. In fact, a "balloon" that is completely vacant inside will be much more buoyant than one filled with hot air, helium or hydrogen.
The problem is that there is no known way, using materials and methods known to us, to create a structure strong enough to withstand the pressure yet light enough so that the entire assembly is buoyant.
Regarding your last question, reducing the air pressure by half in a rigid sphere would be the same as reducing the density by half, at constant temperature. The buoyancy force you would gain would be Fb = (ρ - ρ0) v g, where ρ0 is the atmospheric density and ρ is the density inside the rigid sphere. But like I said above, it is impossible to build a rigid sphere strong enough yet light enough so that the net force on the sphere is upward.
2007-01-31 03:14:21 · answer #1 · answered by . 4 · 3⤊ 0⤋
The ball wouldn't float unless the material it were made of itself is lighter than air, which I don,t think is possible.
And your reasoning about the 7 pounds pressure is flawed because pressure is exerted in all directions, you would have 7 psi both in the upward and downward directions ( and the sides a s well.) So, in effect, net upward force would be zero.
Interestingly, it is possible to make an air-filled ball float.
Filling the ball with sufficiently hot air will make the overall density lesser than that of the surrounding air, thereby making the ball float...
2007-01-31 03:21:43 · answer #2 · answered by Anonymous · 0⤊ 0⤋
You got a few things confused. The 14.7 pound per square inch of atmospheric pressure is not linked to buoyancy. For this, you need to reduce the mass per unit volume, so that displaced air from the outside creates buoyancy. Air weights about 0.016 lb per cubic feet, this is how much lift you would get from a 1 cubit feet of vacuum; one pound for 61 cubit feet, or a cube nearly 4 feet to a side. Now, add the bulk of structure required for this vacuum not be crushed by the outside 14.7 pound per square inch pressure, and you have something that needs to be built more like a steel safe than a balloon.
2007-01-31 03:28:13 · answer #3 · answered by Vincent G 7 · 1⤊ 0⤋
Theoretically possible but undoable in practice.
Air pressure of 14 psi is not what would cause the ball to float. Air pressure pushes on all sides equally regardless of weight.
It is rather the MASS of the air removed, which must be greater than the mass of the outer structure. Clearly, this can only happen if the outer structure is impossibly light.
2007-01-31 03:23:43 · answer #4 · answered by Keith P 7 · 0⤊ 0⤋
People have been working on this idea for a long time. The problem is that to make a structure that can hold the vacuum requires materials that would make it heavier than air. The air pressure would be pressing on this structure and it would need to be strong enough to avoid being crushed. It would also need to be strong enough to keep the air from entering. This takes a lot of structure.
There is hope that one day new materials and building processes come along to make it possible.
2007-01-31 03:15:34 · answer #5 · answered by A.Mercer 7 · 2⤊ 0⤋
It would float up to the level where its overall density (in grams per cubic meter, for instance) is equal to that of the surrounding air.
If it is more dense than the air at ground level (as most solid objects are), it won't float at all.
This is called buoyancy.
http://www.stuffintheair.com/Archimedes-principle-of-buoyancy.html
2007-01-31 17:16:40 · answer #6 · answered by Radiosonde 5 · 0⤊ 0⤋
Firstly, The moons gravity is 1/6 that of earth.. Secondly, Of course it would be possible to tee up a golf ball ? Why wouldn't it ?
2016-03-28 22:17:55 · answer #7 · answered by Anonymous · 0⤊ 0⤋
only if you can find a solid material rigid enough to do the job that is lighter than the air the ball would displace, good luck with that one ! lol
2007-01-31 03:25:14 · answer #8 · answered by wyzrdofahs 5 · 0⤊ 0⤋
nope, there is gravitational force right?
2007-01-31 03:14:07 · answer #9 · answered by lakshmi d 2 · 0⤊ 2⤋