A Perpetual Motion device

[helloha]

There are two ways to raise the water level;
one is using the displacement of objects,
the other is using the weigh (or force) of the objects.

Let's start from the fundamentals, comparing these two ways, then slowly work the way up later.
- refer to image
- one of the image show the example of using the volume of wood, submerge in the water, to raise up the water level
- the other image, although it's not showing water level rising, but at a later part, it can show how to use weighs to rise the water level (or just raise the water)

[Tarsier79]

I understand very well how hydrostatics work. I was specifically referring to your picture where the fluid magically shot up to overflow back into itself.

The whole concept is based on lever and buoyancy,
and knowing how to use water as a weigh and when to use water as a fluid.
What is only needed throughout the process is .... open/close valves & lock/unlock latches

You didn't explain the mechanism required to move the water up to the required level.

[helloha]

Be patient, will get to there,
and the rise of water (or the mechanism) is based on the weigh of object, not the displacement

- from the image that use displacement to rise the water, the water level at the outlet and inlet is the same
- while for the other image, the water level at the inlet drop and the outlet rise (btw the hydraulic utilizes this type)

[helloha]

The image shown
- using the weigh of the wood, the heavier it is, the higher the water rises
- so if the weigh is 1000kg, imagine how high can the water rises up.... assuming the whole system wouldn't burst or crack or break first

Not shown in image, other factors that can contribute to water rising is
- the smaller the area of outlet, the higher the water rises
- the bigger the area of inlet (meaning the wood also get bigger, which result in heavier wood), the higher the water rises

[Art]

"- the smaller the area of outlet, the higher the water rises "

-------

I'm afraid it's not quite like that Helloha .

This is one of those counterintuitive situations . While it is correct that the area of the cross section of the pipe is important in calculating the pressure in hydraulics ,what is actually happening in your example is that the pressure you're exerting on the outlet is actually , in addition to lifting the weight of the water in the outlet , also lifting a column of atmosphere with the same surface area as the outlet .

What this means is that the water in the outlet pipe will rise the same distance as it will in an outlet pipe of say twice the diameter .

If you put two outlets of different diameters on your above diagrams , the water level will be the same in both . Atmospheric pressure will level them ! .

If it weren't the case it would allow for a very neat perpetual water flowing device . If the water rose higher in the thin tube then all you would have to do was put an overflow outlet just below it's maximum height and allow it to flow into the lower water level of the thicker tube .

If Only ! : )

[Tarsier79]

H. in your diagram, you are using the water as the weight. The water is the same density as the water below the "wood", or piston. You state it is a buoy, so the pistons density is less than water.

If your piston was the same density as water, why would the water level in the output not be exactly the same as the water level above the buoy on the input?

[helloha]

Tarsier79

I'm not really sure what you're referring to the density of water, but just to clarify, don't be confused by the buoy.
At this point in the image, the buoy is not submerged in the water (or it's not floating in the water), it is resting on the surface of the water below it, just like the wood example in previous image, or basically the buoy is the wood.
Which mean the weigh of the buoy itself will also affect the water rising, and the bigger the buoy, the more heavy it is, and the more the water level rises.
Anyway I made modification to the image, is the water level what you're expecting ?

[helloha]

Art

If you put two outlets of different diameters on your above diagrams , the water level will be the same in both . Atmospheric pressure will level them

Is the image below shows what you're describing,
also attach a calculation using the formula used by the hydraulic example to show the different between the area of the outlet, and its effect on the distance going up.
Not sure how the atmospheric pressure levelling them, but that pressure and gravity will definitely affect the water raising up, but then again there's no need to raise the water so high up in the first place. If the input force is only 100kg, then the raise needed would probably be less than 1m.

[Art]

Sorry Helloha, I meant if you draw both different size outlets side by side in the same tank, Or if you connect the two separate tanks with a tube or passageway to make them into one big tank , the height of the water will be the same in both outlets .

Your calculations for the forces and the height would be ok if the input force wasn't coming from the weight of the floating wood . But because it is , the weight of the atmosphere (which is also getting its weight from the same gravity force ) is acting on the outlet and exerts a back pressure on the wood which limits the height that the water can rise up the outlet tube .

If you put two tubes of different diameter in a bottle of water and force the water into the tubes you should see the levels in both tubes exactly the same providing both tubes are open to the atmosphere .

I hope that makes sense .

[Tarsier79]

Im pretty sure if you make the output area smaller, the output stroke will be more, but give you much less force

[Tarsier79]

I like to simplify hydraulics. Art is correct about output height being the same regardless (under specific conditions). I normaly draw the system on grid paper, and use whole numbers for simplicity.

It is a simple leverage ratio.

area 1 : area 2
= force1 : force 2
= distance2 : distance 1
= leverage2 : leverage1


as you decrease the area 2, its leverage becomes more, hence the fluid height remains the same.

I didn't even look at your formulas below. The clutter is a little offputting.

[helloha]

Art

if you draw both different size outlets side by side in the same tank, Or if you connect the two separate tanks with a tube or passageway to make them into one big tank , the height of the water will be the same in both outlets

Yep agree, the water height is the same,
attach is the image below
Having two outlets (or more) is something interesting, good thinking... maybe can utilize this in the future

Your calculations for the forces and the height would be ok if the input force wasn't coming from the weight of the floating wood

Easy, the input force came from the weigh of the water, resting on top of the wood;
or the input force does came from the wood, but to add on top of it, an extra and even heavier input force from water,
like 10kg wood and 100kg water, total 110kg etc

I think when people see the word "wood", they assume it's floating,
but to float, the wood need to be submerged in the water, at least a portion of the body are to be in the water.

- When the wood is "floating", it is using its volume or displacement to raise the water level;
- if the wood is heavy and floating, it mean more volume submerged in water, more water raise;
- but when the wood is totally submerged under water, the weigh of wood will not affect the water raising.

- whereas if the wood is on top of water, not floating or submerge in water;
- the heavier the wood, the more water rises.
- then add the weigh of water (assuming is even more heavier than the wood), even more water rises.

[helloha]

Tarsier79

the output area smaller, the output stroke will be more, but give you much less force

Yep, the force will be less,
so the solution.... build bigger (like build bigger wind turbine, build wider solar panel etc)

But a question which I'm not sure, having smaller output area, does that mean it will also last longer; if less volume of water coming out of the output, then it will also take longer to complete the process... but with that huge input force pressuring it, the rate of water flowing out should also be fast ?

I didn't even look at your formulas below

Not my formula, it's from the textbook, I'm just a copycat.... anyway I also don't bother about those equation, let the specialist do the calculation

[Art]

"Not my formula, it's from the textbook, I'm just a copycat.... anyway I also don't bother about those equation, let the specialist do the calculation "

-------

---Thats no problem ! . After you finish practicing on this you will be a specialist ! : )

If you want to calculate how high the water rises in the outlet tube you can do a relatively simple approximation by converting the weight on the (wood) piston into volume of water equivalent to that weight and measuring how high the surface of that water is above the piston .

For simplicity imagine the piston as thin and weightless . Convert the weight that you are applying to the piston to volume of water , eg 100Kg weight multiplied by the density of water which is 1.0 (by definition) equals 100 Litres or 100,000 cubic centimeters.

Divide this by the area of the piston (lets say to make it easy that it is 1000 square centimeters) and that gives the height of the water in the outlet over the height of the piston , ie 100,000 /1000 = 100 centimeters height (or one meter above the level of the piston ).Thats how high the water will rise in the outlet pipe against the weight of the atmosphere when forced up the outlet by 100 Kg of force applied to a piston of 1000 square centimeters .

1000 square centimeters is only one tenth of a square meter but it will raise the water in the outlet by 100 centimeters . If you make the "piston " one square meter the 100 Kg force will only rise the water against the atmosphere by one tenth of a meter (ie 10 centimeters).

This is why I think its counterintuitive when dealing with atmospheric pressure, - because we don't think in terms of the atmosphere as having a lot of weight its not that easy to see why "piston leverage" doesn't work for us to drive water to great heights .

[helloha]

Art

Just checking, given the input area of piston is 1000 square centimeters, what's the output area?