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Surface tension?
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.
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?
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.
Must be magic, like you're thinking.
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
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.
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.
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.
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.
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.
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.
S Q U A R T
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.
because that force is translated into making the ball spin