Because an engineer tested this and found the correct water pressure to lift the sphere just a little bit on the water. And the craftsmanship needs to be spot on. No dents or big imperfections on the sphere, a perfect fit with equal water dispersal on the pedestal.
It can happen to cars too when rain water accumulates on the road. If they go fast enough the tires lose contact with the ground and the car will become unsteerable.
Orbs were pondered.
The house pressure is between 50 and 100psi. Pounds per square inch. So now figure out how many pounds your ball weighs. Then divide that number by the pressure you have. This gives you the area you need. Make it slightly larger by 10%. Then figure out the radius of the circle you need to make that area. Cut that circle into the bottom part. Super easy, you just need a CNC grinding machine. Now take the ball that was also made by the CNC magic machine and lif it over the hole. You’ll need like a hundred buddies for that. Apply the pressure to the water and viola! The sphere floats! But as it floats, the water escapes thru the sides so it can’t fly away, it can only float. To make the water come out at some crazy pressure just make the circle a little smaller and increase your pressure. The smaller the circle, the more pressure you’ll need. It’s totally possible to have a ball that floats and sprays everyone around. You just have to overcome the boundary layer pressure. The speed of any liquid near a wall is 0. So the liquid right next to the wall is what can move. This motion crates a boundary layer where the speed of the liquid goes from 0 at the wall to some larger amount. A small gap means you’ll never hit the full speed of your pump. A big gap means your pump can develop a full speed flow. So in short, big pump, small ball, big circle ⭕🔴 will get you a flying ball that splashes everyone and a big electric and water bill.
We had one at the campus of my last job that was carved with a globe. You could grab onto it and spin it around if you could get enough friction.
How does the whole surface of the marble stay wet when the water comes out the bottom? Surface tension and chaotic motion causing the marble to spin every which way?
Yes, I’ve seen some of those marbles that haven’t spinned for a while and top of it is dry.
Yes. But if you stop one by grabbing it the top half will indeed dry off, and even fairly quickly if you do it on a hot summer day in the sun.
Water squirts out under pressure from the tires
Here’s some advice - when people take the time and effort to answer the question you asked, don’t immediately accuse them of being wrong about the thing you already said you don’t understand. It’s foolish and a just a dick move in response to people going out of their way to help you.
not quite unfortunately https://en.wikipedia.org/wiki/Aquaplaning
One day, you could be in for an unpleasant surprise. This is why you should slow down when it rains.
It’s a balancing act.
Water is not compressable, unlike air. When you put pressure behind the water, in the case of the marble ball, it simply moves the ball up out of the way. As the above comment says, it needs to be a very smooth matched set, both the ball and the pedestal have to match curves. This way the water is forced out evenly all the way around. Since you don’t NEED the water to be super duper pressurized, the water doesn’t spray out.
Here’s one way of thinking about it: my pressure washer is 3000psi. When I put the nozzles on it, they spray super hard. If I take the nozzle off, that same water is merely flopping out of the end, looking like normal water out of a faucet. However, the more you constrict the opening, the more “spray-like” things get. The marble ball is the pressure washer without the nozzle. The water just flops out. But the more you force the opening to constrict, in this case by putting more and more weight on the ball to keep it from moving, then you will begin to see spraying, coming from the path of least resistance, likely an imperfection in the marble surface.
As for driving, Water splashes out from under the tires when you’re going slow enough.
Speed up, thus increasing the forces acting on everything, and the water really doesn’t like you being there.
If you take a garden hose and put your finger over the end, yes at full pressure water sprays everywhere.
Reduce the pressure both on your finger and in the hose, and the water no longer sprays out, it simply pushes your finger out of the way.
But that’s why I’m askingbwhy the heavy marble ball doesn’t force the water to spray out.
A light foam Ball would be like you described.
A heavy marble or granite ball will constrict the water forcing it out under pressure
This is “1kg of feathers vs 1kg of stone”
The weight of the ball is irrelevant if you have just enough pressure to lift it. When you add MORE weight to the marble ball, you will get the spray effect.
From what I understand, the water would spray out if it could, but there’s not enough room, so the force instead pushes the ball up to give more room, but the engineer tailored the forces just right so that once the ball is lifted, the force that would have made the water spray out is already used up, so it doesn’t spray. There’s only enough force to spray or lift, not both.
This is “1kg of feathers vs 1kg of stone”
The weight of the ball is irrelevant if you have just enough pressure to lift it. When you add MORE weight to the marble ball, you will get the spray effect.
Imagine a trickle of water. A heavy marble ball might construct it and force it to spray out, but a foam ball of the same size would not be heavy enough, and the water would push it up and out of the way.
So if your marble ball is forcing the water to spray out, increase the flow of water from a trickle up to whatever it needs to be for the water to lift the marble instead of spraying out.
(Is that right?)
Take your hose
Just barely turn it on.
Hold it up at eye level. The water fills the ending and slowly overflows the hose nozzle
Now take a marble slight bigger than the end of a hose and hold it tightly…water pressure will build and water will squirt out under pressure.
I don’t see how the heavy granite balls don’t do the same
Now take a marble slight bigger than the end of a hose and hold it tightly
I don’t see how the heavy granite balls don’t do the same
The giant granite ball is not being held tightly. For your example just set the marble atop the opening of your hose. The water will continue to slowly overflow the end of the hose. Now if you exert additional force on the marble that’s on you.
You should do this yourself and take a video. Share it and speculate with us why the objects in your video behave the way they do.
You can make a small model of this yourself using a marble and a dribbling hose. Try it.
If you tried it with a bunch of different weights and sizes im sure you could get the same effect eventually.
An any hose and an any marble, not likely. This is a precision feat of engineering, with minds sharper than ours dedicated to the study and application of these forces.
If any monkey could do it then it wouldn’t be impressive.
My advice: (not to OP.) Block this guy. I don’t think he understands that he’s not on Reddit and karma doesn’t matter. He’s trolling and wasting your time. He asked, people answered, and now he’s just arguing. Troll behavior. I’m blocking him, and my Lemmy experience will be better for it.
tbh i’m not blocking these trolls because the comment section is still quite high quality lol
The way I like to put it. There are no stupid questions, only stupid people
“There are no stupid questions, but there sure are a lot of inquisitive idiots.”
If the water pressure was high enough to spray out, the ball would simply fly off. It’s the perfect equalization of the weight if the ball and the pressure of the water. You can do this yourself at home. Try this:
Find a marble that fits the opening of your garden hose perfectly. The hold you garden hose upright, place the marble on top (do NOT hold it in place), and begin turning the the valve until you reach the correct pressure. You’ll notice that without enough pressure, nothing happens at all, and with too much pressure, the marble will fly off the top of the hose.
It’s a balancing act
Now do a marble that weighs 500 lbs.
It’s gonna spray
Why ask a question if you think you know better
Marble has a density of 0.098 lbs/in3. So a 500lb sphere has a volume of 500lb/.098lb/in3= 5102 in3. That gives a radius of (5102 in3 * (3/(4pi)))(1/3)= 10.68 in.
Let’s say the bowl it sits in has 2/3 the radius. So 7.12in. That makes the enclosed surface area pi*( 7.12in) 2= 160in2. So 500lbs/160in2 = 3.14 psi. How fast do you think the water will spray out at 3.14 psi? Without any drag, out of an ideal nozzle, it would be 6.5mph. However, the pressure will actually be higher in the middle and tapers off to 0 at the edge thanks to the flow diverging and drag. So really the pressure drop at the opening is even smaller.
There’s a lot of lifting area which means you don’t actually need much pressure. You can lift entire buildings with large water bags.
This guy.puts his physics where your opinions are
Bigger marble, bigger hose. It’s the same principle scaled up.
This one weighs 9 tons
https://en.wikipedia.org/wiki/File:Reaching_for_the_Stars.jpg
The variables in this equation are:
- Diameter of marble
- weight of marble
- diameter of “hose”
- water flow/pressure
Along with some friction outliers, these can be adjusted to find an equilibrium.
Pressure is measured across surface area. The same way buoyancy is measured by water displacement. A larger object has more surface area. 1 PSI of pressure won’t be very much if the object only has 1 square inch of surface. But it would be a lot of pressure if the object has 500 square inches. 30 PSI is enough to keep your car off the ground. A few PSI would be enough to lift a 500lb rock if the surfaces were prepared properly.
For every weight of ball (within a certain density limit. Won’t work with a black hole, for instance) there’s some pressure and volume of water that will balance the weight and size of the ball perfectly to create a thin layer around the entire surface. Once the ball becomes too dense, there’s no volume/ pressure combo that would do the same (the weight would require too much pressure by volume of water, so it would either stop it or fly full force by while barely levitating the ball). But I don’t think whatever density that would be is found in pressures you could find on earth
Lol
It’s all about the pressure; more weight needs more pressure but they tune the pressure to match the weight of the ball.
I know this is No Stupid Questions, but has something happened to Lemmy?
Is someone inflitrating lemmy with a load of troll accounts designed to rile up outrage?
Totally suspicious behaviour lately
It could be related to the unseasonally hot weather in Europe/other places?
Honestly reminds me of when r/Canada was suddenly very pro-USA and anti everything good about Canada. Suddenly every article posted was about failing healthcare, “immigrants bad” and needing to drill more oil. Canadians bailed en-mass.
For some reason, all these accounts speak the same way. Like they’re all from the same area or something. Really obvious if you catch writing mannerisms.
I have this guy tagged, he’s been here a while and started by denying the artemis II launch and other stupid shit.
I kinda get what you mean, there’s this other person using lemmy as his personal IT 101 professor, his posts annoy the shit out of me too. But apart from that it’s them and this guy when I think about idiotic posts
Why would you be outraged by this??
Go take a look at the responses to comments by op.
https://en.wikipedia.org/wiki/Kugel_fountain Is it this kind of thing you’re asking about?
If it were concentrated to one small hole, it would. The same way putting your thumb over the end of a water hose will make the water spray farther. The wide base around the bottom of the sphere gives enough space for the water to come out without squirting far.
Here’s one that does squirt out more than most: https://youtu.be/yEeEU-WRbP0
Maybe they have the water pressure too high, maybe the tolerances are too low, the sphere doesn’t fit the cup quite right, so they need higher pressure for it to spin. Considering the shape of the base, I think they designed it this way, though. I like the water splashing out of the bottom, that makes it more interesting.
The water being that dirty makes me think they’re flushing it out to finish it, not demonstrating the final product. Maybe there’s some sealant or fine abrasive to help the final fit.
Why should it squirt out? Who would want that? Think about basics:
Pressure is force divided by area.
The weight of the ball (downward force) equals the upward force from the water pressure, then it can float.
You want the water pressure to be about 1 bar (equal the air), so it does not squirt out.
From that you get: weight of the ball divided by the partial area of the ball that is in the water equals 1 bar.
That’s how big and how heavy your ball must be, then it works.
It’s not floating though
It’s more like hydroplaning
At some point the weight of the ball would close off the water and force it out like squirting
It’s more like hydroplaning
You mean the thing that, in this very thread, you were arguing does not exist?
What are you even doing? Seriously.
Hydroplaning squirts out a lot of water
The water comes out at a single point at high pressure below the sphere.
It then travels out and exits all around the sphere.
The water can be pumped below the sphere very slowly, but at high pressure, and that way still lift the sphere.
The water doesn’t get squeezed and accelerate towards the outside edge, because as it flows outward, the circle gets bigger. The area expands.
Hence it slows down, drops in pressure, and comes out at a trickle.
It’s not like pinching the end of a hose. It’s like adding a kink in the hose before the end. There is huge pressure before the kink (the water that lifts the sphere), and after the kink the pressure is super low (the water exiting from below the sphere). It makes the water slow down and come out at a trickle. Even though the pressure before the kink is huge.
hydroplaning
Then I don’t know.
GMU’s Manassas campus has something like this; I think it has something to do with the pressure of the water within the basin resulting in an ultra-thin, low-friction “cushion” for the ball to rotate on.
To oversimplify the answer, if you put a strong enough ‘garden hose’ beneath the floating sphere, you would still get that ‘spraying effect’ like you do with a garden hose. However, the sphere would no longer ‘float’ in place in thst case.
Keep in mind that the floating sphere ‘uses the energy of the spray to stay aloft’, balanced against the weight of the sphere. As a result, there is not enough energy left to make the water spray outward like the garden hose does.
There are many different factors at work to keep the sphere afloat, such as the curved base below it, matching the sphere’s curvature. Again this is an oversimplified explanation, to help explaon the basic concept.
Must be magic, like you’re thinking.
S Q U A R T
because that force is translated into making the ball spin
Surface tension?
