3rd working machine you gandmother could make _2nd Law crushed

[TinselKoala]

You start with a thing that looks like a "boot", with a "foot" chamber sticking out to the side at the bottom, and a tall skinny "leg" portion that rises up much higher. There is a water- and pressure-tight door separating the foot from the leg, and there is some kind of water- and pressure-tight lid you can put on the top of the foot to seal it tight. This lid is open to start, and the door between foot and leg is closed, and both foot and leg are filled with water. 

Now you have a box that is heavy but is of such a volume that it is just barely negatively buoyant, that is, it just barely sinks in water. So when it is in water, it doesn't take much force to lift it up, as long as it is completely submerged.

Now you lift this box up from the ground outside the foot using a heavy crane, lift it over the wall of the foot, and place it into the foot. It sinks in the water that is in the foot. But the water level in the foot rises! You have added a volume of box to the fixed volume of water in the foot, and now the level of the water in the foot is _higher_ than it was before you added the box. Right? Or perhaps it just runs out onto the ground over the edge of the foot wall, but that's pretty wasteful, don't you think? Also messy.

OK, so now you put the watertight lid on the foot, even with the top of the water so there is no air in there.  Now you can open the connecting door between the foot and the leg. Slide the box over into the leg and close the door again. Remember that the level of water in the foot is still higher than it was before you placed the box in there, or you have lost a volume of water over the edge, either one. Right?

Now you can lift up the slightly negatively buoyant box all the way up to the top surface of the water in the tall leg of the boot. This doesn't take much work, you can even do it with a weak 12-volt winch. But then... you have to lift the box up out of the water to place it on the receiving platform, and this takes a bit more work... since the box is actually quite heavy out of water. AND--- the water level in the leg of the boot DROPS, because you have removed the volume of the box from the leg. Let's recap: you have lifted a box from the ground to the top platform, and the water level in the FOOT is HIGHER than it was before you started, and the water level in the LEG is LOWER than it was before you started. You have not only lifted a box, but you have LOWERED an equal volume of water from the top of the leg, down into the foot of the boot.

Go ahead and do it again with another box. Now you've transferred another volume of water from the leg to the foot. The water level in the leg is now lower by another increment of volume equal to the volume of the box and the water level in the foot is now higher by the same increment.  Repeat ... until the water level in foot and leg are equal and you are lifting your box way up off the ground to get it into the foot, and way up out of the water in the leg with a crane to get it to the upper platform.

The only way to get around this is to have the water in the leg constantly replaced, as you move your box from the foot to the leg, which transfers an equal volume of water _out_ of the leg and _into_ the foot. Got a convenient river at the top of your boot leg to replace this water? At the top of the pyramid? No? Then your device will eventually run out of the _stored energy_ represented by the head of water in the leg of the boot. It is this stored energy, released as power of water falling, that is helping you to raise up that seemingly light box to the top of the _water level_ , which is falling one box volume at a time, in the leg of the boot.

Looks like Newton isn't "crushed like a bug" after all. No, it is Archer Quinn who is crushed like a bug, on the windscreen of Conservation of Energy and the conservative field of gravitational force. There is no free lunch to be had from buoyancy, which is just gravity acting in a way that is difficult for some people to grasp.

[tak22]

Hi TK,
Nice explanation of the worst case interpretation. Can you do another one where the "heavy box" is actually empty and the weight is the in system water? Empty box lowers into the boot, fills with water except for enough air to remain buoyant, enters the leg, box rises up/pulled up, water drained/emptied to fall through a turbine back into the boot, rinse and repeat?
I have no prediction on whether the losses will be offset ....
tak

[TinselKoala]

Hi TK,
Nice explanation of the worst case interpretation. Can you do another one where the "heavy box" is actually empty and the weight is the in system water? Empty box lowers into the boot, fills with water except for enough air to remain buoyant, enters the leg, box rises up/pulled up, water drained/emptied to fall through a turbine back into the boot, rinse and repeat?
I have no prediction on whether the losses will be offset ....
tak

If you have enough air in the box for it to "remain buoyant" it will still displace a volume of water when you put it in the foot to begin with. So you are in the same trouble as before. By the way, I am not describing a "worst case" interpretation, I am describing exactly what Quinn put forth in the document, except I am including what he (deliberately?) left out: the displaced volume that winds up transferring water (stored energy of position) from the top of the leg down into the foot, doing work as it goes and requiring work to replace.

So why not just use a bucket? Lower the bucket down the leg to the bottom then hoist it up. If the bucket is heavier than water it will sink by itself. Then you can bring up a bucket full of water from the bottom of the leg, to the top level, with only the cost of lifting the weight of the bucket itself (minus the weight of the water the bucket shell itself displaces, which presumably can be made very small with magic bucket-materials), since water is exactly neutrally buoyant in water... duh. Now you can pour your water from the bucket through your turbine... and then where does it go? The water level in the leg has now dropped by one bucket-volume. If you pour the water through the turbine into the top of the leg... you have to have your turbine above the surface of the water and the only work you can get is the work from the height above the _surface_ and back to the surface, through the turbine. In other words the whole affair of lifting the bucket up through the column of water is wasted and you are just pouring water from the bottom of the turbine, lifting it up to the top of the turbine, and your turbine is only returning part of the work you put in to lift that water thru the air.
If you pour the water thru the turbine at the bottom of the leg, hence using the entire head of water pressure to drive the turbine... how do you get the water back into the leg? You can pump it back up to the top, with the usual losses, or you can pump it into the bottom; either way you still have to pump it against the full head of the water pressure. Or you can let the water run out of the bottom and forget about it... and then you are running on the stored energy of the water column which is getting lower all the time. You might as well just dispense with the bucket or box and just punch a hole in the bottom of the leg and put your turbine in the flow from the hole.... and when the water runs out without being replaced from the _top_, you are once again out of the stored energy represented by the water head in the leg of the boot.
No, the losses will not be offset, and this is not a "prediction" it is a verifiable fact. Unless you have an outside source of energy replacing the water you will quickly run out of the stored energy that you put into the water column to fill up the leg of the boot in the first place.

[tak22]

"worst case" was just a poor turn of phrase, I just appreciated you doing a full walk through. Also, I used too few words so you didn't quite get all of what I meant last post so I'll add a few more thoughts:
- the turbine is positioned just above the boot so it gets maximum head pressure.
- the box is exactly the size of the boot minus enough space to allow enter/exit
- the box lowers into the boot with a bottom opening so it fills with water already in the boot
- when the box reaches the top it is drained directly into the turbine or a head pond, then moved empty to be lowered back to the boot
still no prediction from me, just tossing out refinements 


tak

[TinselKoala]

"worst case" was just a poor turn of phrase, I just appreciated you doing a full walk through. Also, I used too few words so you didn't quite get all of what I meant last post so I'll add a few more thoughts:
- the turbine is positioned just above the boot so it gets maximum head pressure.
- the box is exactly the size of the boot minus enough space to allow enter/exit
- the box lowers into the boot with a bottom opening so it fills with water already in the boot
- when the box reaches the top it is drained directly into the turbine or a head pond, then moved empty to be lowered back to the boot
still no prediction from me, just tossing out refinements 


tak

This is equivalent to the bucket I described above, then, and the box itself is just the same as the bucket.

If the turbine is at the top, then your available pressure head is just small. If you drain the water out of the system thru the turbine into a pond at the top, you have only the small head and a short fall of water, and the level in the leg of the boot drops. If the turbine is at the bottom so you get the full head pressure, then you still have to move the water back to the top, and you can't use the counterweight of the now-empty, light, box to do it because it's not nearly heavy enough to offset the weight of the water you have to move. Again, you will either run out of the stored energy of the water column in the leg, or you have to use an external "river" to replace the water in the leg that you are pouring out with every boxful you lift up. Or you have to lift the boxful of water _out of the water_ to pour it thru a turbine at the top so that it falls back into the top of the bootleg and thus you only have a small head, equivalent to the lift _out of the water_ that you did to get the box full of water up to where you can empty it into the turbine.

Still not a prediction from me either, just a simple statement of fact: There is no way this device will work by anything except the stored energy of the water column, which will either run out one bucket (box) volume at a time, or will need to be replaced by an outside source of energy greater than you are recovering from your turbine and lowering mechanism.