Just guessing, but I'd think it would be weights, to allow him to control the buoyancy and position.

Lower water pressure would inflate the swim bladder, increasing the buoyancy. Higher pressure makes the bladder easier to empty, making it easier to sink.
You get this effect when scuba diving - it is harder to get down from the surface than to get deeper when you're already several feet below.

They aren't wrapped in wood, but if this is uncoated pipe, some will lightly tack weld a ridge or piece of scrap barstock to the OD of the pipe to keep it from rolling when building the stack; they aren't there to prevent this type of major rolling action. At around 1:33 you can see one of these going over the edge. Just guessing, but these look to be in the 20" to 30" diameter range with plenty of length, so they're just really small ships with the ends cut off and will float for a bit until well flooded - lots of surface area there for some buoyancy, and I've seen 40 foot joints of 20" diameter casing float near the surface for 30 seconds or so when a bubble gets trapped temporarily inside before burping out and sinking to the bottom. At around 2:15 you can see the big reddish block with the vertical groove right on the corner of the load platform about 1/4 of the way up the frame. That's where normal humans stab the stake or pipe to help contain the load (so, the vertical pipe or solid stake goes in the hole, the load is built, and no rolling can occur - momentum is the killer here, so if you keep things from rolling, life is good. This was an excellent example of how not to load pipe on a barge / ship.

http://www.dummies.com/how-to/content/understanding-buoyancy-using-archimedess-principle.html

The ball has air in it. The jumper used the artificial force of his weight to carry the ball well past it's buoyancy point. Since every action has an equal and opposite reaction, the ball skyrockets.

Drop impact is different.

Problem 1: Tip toward the wood, as the wood will lose more buoyancy from the air than the lead.

As for the extreme case here, let's use the helium balloon. You tie the helium balloon to the right hand side of the scale. Now, to get the bar on the scale horizontal (balanced) you need to hang the lead weight closer to the fulcrum but on the right hand side of the scale too.

Now remove the air.

The balloon was only pulling up because of the air. Without the air it will hang down. So, we now have two things hanging down on the same side of the scale, so it's very obvious which way the scale will swing...

Problem 2: pi*20m Circumference = pi*diameter. Poles increase diameter by 20m. Really not sure where the 'extreme case' comes into this though?

In the opening question she blew it. What if the rock is lava rock, which is LIGHTER than water? That means you can't figure out the answer without knowing the density of the rock.
Archimedes equation is only useful in figuring out weight for things that are buoyant. Anything more dense than water (or whatever medium you're in) will only displace it's own volume in water, not it's mass.
That's why I think the wood block should weigh more in a vacuum. It displaced more air, so was more buoyant, and so had more buoyancy to lose. It seems to me she set it up poorly again, because if they weigh the same in air, but are different densities, they would seem to need to have different masses to achieve balance, but she said they have the same mass, but I think she should have said 'they weigh the same'....just as @Barbar and @Stormsinger indicated above.

You're absolutely correct. Especially the last part (this is a sloppy video). If they balance on the scales -with- an atmosphere, they won't balance without one. And in atmosphere, the wood will have have more buoyancy than the lead (my screwup).

The rigid-hull inflatable uses the tube more as a stabilizer than flotation. They only become necessary in rough seas or hard maneuvering. The tubes are attached to a short-sided fiberglass or aluminium hull, which provides the buoyancy. At the end, you can see them slowly making towards home.

Smaller Zodiacs use the tubes as the hull, with just a sheet of rubber hanging between the tubes as a floor, so when the tubes lose air they completely collapse. In order to carry more than 3-4 people, you need a rigid hull for strength. Otherwise it would just flop all over the place like an inflatable life raft.

Flooding and evacuating ballast tanks around a neutral buoyancy and the shape of the hull. He goes like half the speed a diver can swim at, so there's not a lot fins would do to help anyway. Probably slow him down even further due to drag, to be quite honest.

I was wondering if it separated, but I couldn't see the lines in the video (although the thumbnail does show a decal distortion) and these days all sorts of people are creating vehicles and run on land and water, but the front end certainly didn't look like it could do proper buoyancy. I wonder if that craft is custom built. Def some money there.

It's not toodifficult to be upside down like that with a dry suit. When you're first learning to dive with a dry suit it's actually a bit difficult to master NOT doing that. Any excess air within the suit will tend to bubble up to the highest point of the suit, so if you just tilt a little, the air will go to your feet, and turn you vertical.

That would USUALLY be fairly bad technique unless you were intentially trying to keep your fins away from the bottom while you were looking at something or gathering something, etc. It's more difficult to control your buoyancy and assecnt/descent rate, but since they're just bumping against the ice, that's a non-factor.

All that said, it's probably pretty difficult to make it LOOK normal while upside down performing all those actions.

This is gonna be long but please bare with me.

The pressure below the surface of any body of liquid is equal to the density of the liquid multiplied by the depth below the surface, multiplied by the acceleration due to gravity. The result is a quantity in pascals, or newtons per meter squared. To this number we add the pressure due to the atmosphere, 101325 pascals; the sum of the two is the pressure experienced by the koi.

The column of water is suspended by virtue of the vacuum that exists at the top of the column, ie. There is no atmospheric pressure pushing down on the column and hence you can 'support' up to 101325 pascals of water pressure within the column before water in the skyscraper would begin to displace water within the pond (this is how simple barometers work). Remember that the pond is under 101325 pascals of pressure, and that as long the pressure within the column is the same as outside there will be no net flow of water. For instance, the maximum possible height of the column would be 10.3 meters (101325/[9.8*1000]).

What all this means is that the water within the column is at a LOWER pressure (and getting increasingly lower towards the top) than the water within the rest of the pond; in a 10.3 meter column the pressure at the top would be 101325 pascals less than at the surface of the pond. So, if a fish looking for food or perhaps increased warmth were to come across the column and swim inside it they would find themselves at a lower pressure than they are designed for. Their air bladders would swell in the decreased pressure, this would in turn lower the density of the fish consequently increasing they're buoyancy forcing them higher into even lower pressure water, eventually trapping them at the top. As more fish find the tower, more fish are forced to the top where they begin to compete for the rapidly dwindling oxygen supply. Furthermore, freshly oxygenated water would not reach the top of the tower as the water flow would be severely limited through such a constriction. In the third clip you can see what MAY be the fish gasping for air.

In conclusion it seems likely that our German friend has succeeded in creating a fascinating death trap for his fish, and I'd bet that he got up the next morning to find that he had killed thousands of dollars worth of koi. This would also explain why we/I have never seen this design before. Of course, I am assuming that the fish lack the necessary muscle power to get themselves out of this situation, which they may well have, but the number of fish so close to one another seems odd to me. I would of thought that if they could easily get out of the column then they would, if simply to find a less crowded location.
Tl;dr IT'S A TRAP

EDIT: I guess I lost that bet as it would seem that the fish do have the necessary oomph to escape. Though I wish no ill will towards our fishy friends I would still be morbidly curious to see the effects of a ten meter tower.

Not quite so relevant to this video, but the Coelacanth is almost exactly like the earliest tetrapods (and also rather cute). Some of the related fish have legs, or very leg-like fins, and walk on the bottom of the sea floor. The lungs of the lung fish are useful for both buoyancy and breathing... and the fish which can do these things perhaps has an advantage over the larger fiercer fish which can't.
>> ^L0cky:

Heh, I could have kept my mouth shut
Seriously though, that's amazing. They also have a modified swim bladder, just like the early tetrapods.
Like a lot of things in evolution, for all the people that doubt x could evolve from y, there's usually not one example of a solution but many.
>> ^oritteropo:
But some fish do sprout legs, and thrust themselves out of the water. They're even rather cute, see http://blog.nus.edu.sg/lsm1303student2011/2011/03/24/africanlungfish/

>> ^BoneRemake:
>> ^L0cky:
People talk about fish jumping out of the sea and sprouting legs as part of evolution. I think it'd make more sense to be something like this.

Where the F have you heard of people believing fish sprouted legs and thrust themselves out of the water ? Pro Tip: do not hang around those people.

All that mass has to come from somewhere. That's typically the way it works, anyways.

>> ^Payback:

>> ^AeroMechanical:
I find it hard to believe that helicopter can generate enough lift to stay airborne with such massive balls on board.

I believe the buoyancy created by the pure vacuum between their ears provides enough lift to counter the increased weight.

>> ^AeroMechanical:

I find it hard to believe that helicopter can generate enough lift to stay airborne with such massive balls on board.


I believe the buoyancy created by the pure vacuum between their ears provides enough lift to counter the increased weight.