Helium Lifting Power with PSI

This is in no way homework...

I am merely trying to find how much Helium compressed into a 20x20x20 cm. cube capable of lifting over 65 grams would weigh.

I know almost nothing about lifting power nor pressure, so I was hoping to find someone on here that would be kind enough to explain this to me.

I'd be happy to even know HOW to do it, let alone what the answer is.

So please don't assume i'm just looking for an easy answer to my homework. I'm not expected to know this stuff.

You can't do it.

It can't be done. Don't you get it???

It won't work.

You obviously have no concept of buoyancy, displacement or courtesy.

He has weight, so the more you cram in the heavier your (too small) box is.

"I was just given the "Egg Drop" project in my physics class " sounds like homework to me.

Do some research. Maybe Google "helium".

Your job is to learn, not have someone give you the answers.

So you're saying that no amount of He or H will cause a box to float...??

Also, I'm a junior in high school that has an A in AP Calculus, an A in Physics B, and an A in AP Chemistry (among other classes), so I would appreciate it if you didn't act as if I was an idiot and rather act as if I am a student trying to find an answer to a question.

I have never had a class that discussed this subject, nor am I expected to know this. My question is referring to an original and creative idea that I have in mind to accomplish this project that I received today. At this point I am considering all ideas.

Edit: Also, this project has nothing to do with buoyancy or displacement or any of that. I am MAKING it a project that has to do with that, and I do not know very much on the subject, so I came here for some answers first.

The first concept you need to master is that both H and He are heavier than nothing.

They are just lighter than air. So, take your A'ss and do some research on the relative density of gasses.

Why do you think blimps are so big? Consider the concept of a hot air balloon. What makes it float? A difference in density that imparts buoyancy to the body.

Forget it, it ain't worth it. Do you bully your parents, too?

I suspect his parents may be of the sort that are bullying the public school systems into teaching everything but what is practical or valuable knowledge to have in life. You know that real, math, science, physics, chemistry, and general understandings of the fundamentals of how things actually work.

That doesn't make him lazy or rude just poorly informed and misguided about what actually relates to what he wants to know. Or he could just be another one of those kids who was taught that his self esteem is more important than being right or useful.

Naaah. You are too kind. Admit it. He's a freekin idiot. And lazy and rude.

How can anyone claim to have an A in physics, and claim to know about buoyancy, but be unable to do a simple buoyancy problem. We could blame the teacher, but only if his school does not have textbooks, where these answers are easily found.

I'm frightened for our future.

I take you have not spent much time around the schools, colleges and universities of today.

You don't have to know or learn anything about your given subjects class title to get a good grade you just have to be able to test well on what ever they tell you in that class to get a good grade.

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I assume this came from our little tyrant genius.

Anybody know what he said?

Neither have I.

Well, you've managed to show that good grades do not necessarily equal a good education.

Wait. You wrote in post 9:

I know all about buoyancy.

Now, you suddenly know nothing about buoyancy. And you're asking us not to treat you like an idiot?

If it walks like a duck, and squawks like a duck...

I bet you were thinking that you could pressurize the box to above atmospheric pressure to get enough helium into it to lift the box and the egg.

I read this threat & was rather surprised at YOUR rudeness lyn! Read back to how the Jr High kid asked the question and how YOU responded! What is a discussion forum for exactly? To bully Jr High kids so you can feel like a big man or is it for questions and discussions? Which is EXACTLY what he was doing. "We don't do homework here"? It is YOUR attitude lyn that needs adjustment. You're a SERIOUS bully and to a Jr High kid no less, that certainly inserts you into the LOSER department, BIG TIME!

why not ? you're childish in nature ?

So am I.

No, no, don't you just keep putting He in until it floats??????????

The bigger they come, the harder they fall!

Or, put 6 light-headed people in a basket, and don't bother to turn on the propane burner....

This in no way answers my question... at all...

That's not even a helpful fact, and is common sense anyway.

Are you the original poster?

Yeah.

Ok first, you should know how an all metal boat floats in water? If you don't, look it up. This is the principle you are trying to use. Second you must discern at STP the mass of air that occupies your maximum box size. Third, wait a minute... Those two hints should be more than enough for you to do this work. Go earn you grade.

I know all about buoyancy.

Too bad this experiment isn't happening in water...

Also, I know that the box size will be 8,000 cubic centimeters. Knowing this gets me nowhere since I don't know how much helium lifts compared to air.

Those "hints" are not helpful in any way.

1,000 CM³ is one litre.

8 litres of STP (standard temperature and pressure) air weighs around 9.6 gm.

With this 8 litre volume constraint, the limit of bouyancy is...

Please, what physics class are you participating in? In what capacity?

You are absolutely correct! For you those hints are not at all helpful. I'm very disappointed, but not surprised. Well if you can't figure out the lifting capability from a completely theoretical approach, maybe you could figure out an empirical way to measure the lifting capability of helium.

Wrong again. You evidently don't know anything abvout buoyancy, and so far you are being much too stubborn to learn.

Keep looking Padwan! It is indeed about buoyancy!

roughly 1.218 oz per cubic foot.

What do YOU call a helium balloon, other than a buoyant object?

The basic concept you need to understand is that buoyancy is not limited to water. Buoyancy is the weight relation between two masses of the same volume. A boat floats in water because is weighs less than an equivalent volume of water. A blimp floats in air because it weighs less than an equivalent volume of air. A cannonball floats in mercury because it weighs less than an equivalent volume of mercury.

Once you start compressing the helium it will be getting more dense, losing it's lifting capability.

Thank you!

...finally something helpful and someone not being a complete ass about my lack of knowledge on this subject.

If you really must continue this experiment, for heavens sake be careful!

I still haven't recovered from the last experiment.

Thank you,

H. Dumpty

This thread veered down a kind of whacky but interesting road. I like your over-unity/perpetual motion remark, and am giving you a GA just for that (especially the "and no one else has" part)! I reeeeeaaaaly like spinning boxes; they're sooooo cool!

I should point out that upsidasium has negative weight (upsidasium is unique in that it's mass is a vector quantity). Consequently, you should not attempt to measure out a half-pound of Dn on ordinary bathroom scales without first affixing them to the ceiling.

That's a good 'en!

For anything beyond atmospheric pressure, the more helium in the box, the worse the buoyancy gets. At atmospheric pressure, the weight ratio for helium (He) to air is about 4:29.

Hello Guest, Helium balloons float in air because the balloon/helium combination is less dense than the volume of air the balloon displaces (near ground level. Aloft things become a little more complicated). Now, adding more helium (whilst keeping the volume constant, as your box would do - in theory) would *not* make your box more inclined to float. On the contrary. Helium has mass, too, you know, and the more helium you put in your container (which we assume has a fixed volume), the more your box will _weigh_. Truly, Guest, the lightest thing you could put in your box is ... nothing at all. A pure vacuum. Think about it why a vacuum would work best. Why? A vacuum has no mass. Zero. Nada. It doesn't get any better than that! Unfortunately, Guest, one cannot inflate an ordinary balloon with pure vacuum and expect it to keep it's shape for long. A rigid container on the other hand might work - provided the container, when evacuated, and its payload are together less dense than an equal volume of air. Take heart, Guest, this isn't at all complicated. Not really. But, as this is *your* project, I leave to *you* to do the math. It's only fair. ~G2 ('Guest II')

You mean "float your box", right?

Egg-zactly.

(Groan)

Basically, what everyone is trying in a not so very polite way of telling you, is that you would need a MUCH larger box if you plan to use helium. I had the same project in high school. I filled the bottom of the box with crumpled up physics notes, and put the egg on top, thinking the shear power of the physics formulae on the paper would support the egg. It worked.

How 'bout emptying the egg? after all the result of your "egg drop" is to not break the shell isn't it?

If you're going to cheat, go with a hard boiled egg.

You seem to have a glimmer of the basic need here which is to limit the deceleration upon impact. With bouyancy you are barking up the wrong tree. Think instead of surviving an automobile crash. Same principle.

as a brain storming exercise and in no particlar order:

- empty the egg by putting a small hole in both ends and blowing out the contents

- use a balloon filled with the helium (or indeed air) and use the jet propulsion from the balloon to slow the descent

- the "box" can be the required volume to begin with but can develop into a parachute

- does the egg need to be in one piece when it lands ? if not, you could just drop it

- try to use a circular energy storage system (make the egg swing in a circle at the end of a string) with some kind of wing at the other end which would give you lift to counter the gravity loads

- compress the helium by a factor of 5 (compared to its normal volume) into the 20cm box and then let it go so that it jettisons the sides of the box to reveal a balloon that is 5 times bigger thereby making the whole thing slightly heavier than air

- a ping pong ball can be held steady in a hairdryer flow (look on youtube) ; why not put the 20cm box beneath the egg with a fan in it ? i know this doesn't quite work but maybe something else will

- can the 20cm box contain anything ? can it contain one of those model helicopters ?

- turn off the earths gravity for a couple of seconds. seriously. ask your techer to take a trip with you in a freefall plane

my teacher would always suggest using dynamite for any brainstorming idea, just so that everyone would loosen up.

Silly Terrans!

its the venutians you need to worry about. they have no sense of gravity.

As the egg has a permeable shell, the introduction of helium would be detrimental to the development of the embryo, thus negating your attempts to hatch the egg, through body heat transfered by your hairy derriere.

Physics is obviously getting easier - last time I came across this, the cube was 100 mm. (~ 4", not ~ 8") and the drop 10m (33 ft), onto concrete (per tradition)

The the single survivor was then progressively tested up to ~43 m (~140 feet, 10th floor) and only eventually lost to a baseball bat.

^{_{No helium was harmed in the testing.}}

34.5

There is the possibility that a buoyancy exercise could be utilized in this experiment. As i recall from my class, the device had to fit inside the given dimensions before the drop, so as not to exclude parachutes and other such devices. If the original guest wished to they could deisgn a pressurised helium container which upon release would expand and thus become more buoyant and potentially balance out the weight of the container and the egg.

Just a thought!

(mental note, would a carboard box be able to contain 6 atmospheres of pressure?)

Yeah, only if that box will be contained in another steelbox.

Two ways you can achieve your project,

1) Have this made at a zero gravity condition

2) Replace Helium with sand or wood chips etc.

The key to using helium in this project is to shift the reference point far enough to the left to allow the helium to produce 60g of buoyancy. A single stage vacuum pump simply will not get you there. Cascaded vacuum pumps will allow you to evacuate your container down to negative absolute pressure values. This will then allow you to introduce sufficient amounts of helium to provide 60g of buoyancy without having the weight of the helium cause a lifting problem.

Most people don't think of this. Be sure to include comments about this idea on your next test. It will let your teacher know how hard you work on homework.

Please don't forget to thank those here who were able to help you because, when it came to their turn, they did their own homework themselves. These days it's the grade - not the education - that matters, is it not? You must be very pleased.

Congratulations, young padwan, you have made the 'Recent Active Threads' list. A thing that not all of us accomplished Jedi have done.

I would ask that all of us accomplished Jedi go easy on the kids. College students are one thing, but a high school student?! Come on, lighten up. I'm sure there's not one among you who hasn't made a really dumb blunder at least a few times.

After this bludgeoning, I hope he hasn't lost his enthusiasm, his curiosity or his motivation!

This is just like a thermodynamic problem,

you can achieve this floating stuff of the egg of yours at liquid phase of helium at conditions 1-1.5 Kelvin at 25 bars, neglecting the impact. you might as well replace the egg with some other material, because probably your egg will crack at pressure 25 bars.

Ronie

Philippines

On the contrary: the denser the air in the room, the greater the buoyancy of the box/egg combo. About 6 bar would do it (similarly boosting the helium pressure to keep the box from collapsing).