The ten year old really got me stumped on this one...
https://www.youtube.com/watch?v=AC16BeGN6gg
Interesting related
Interesting related link:
http://www.lhup.edu/~dsimanek/museum/themes/buoyant.htm
Essentially I gather the conservation of energy. You rob energy from the system by using the generator which causes it to resist the movement of the chain. I think the real problem would be that magic valve though.
Also this
Also this here:
http://cagematch.dvorak.org/index.php?topic=10758.0
(nearly identical)
The thing is that seal/valve you chose to ignore… In realty that would rob all the energy. But it all ties back to conservation of energy. That is to say; energy has to come from somewhere and if you run a generator from it you remove that energy…
this make me thinking…
in my best english 
The air wants to go up -> less pression between air and water. If the next ball with air comes up it makes the pressure higher again. that means finally no difference at the end… so no rotation.
I think we should build it
I think we should build it
the physics question
(This is Phoenix) you do it and reply back of whyat happend
the physics problem
(this is phoenix)half the balls are in water and half the balls are out of water with air to even it out
try it now
**the valve **
ok here you go.
You can place at the opening some kind of door, meaning two hemispheres that open like a salloon door using some kind
of light spings attached to the doors through each ball passes .
The thing is to overcome the power of the water that holds the doors closed .
This can be accomplished if you find the perfect combination of the gap between the balls and the material in the ball
if you do this the whole thing will work with the help of the springs .
So what do you think ?
No way half the balls could
No way half the balls could be in the water. there has to be more out b/c of the sprockets. (which make the chain system taller than the water. assuming they were evenly spaced. Even still; the reality is it has to do with that vavle. the valve would waste a lot of energy in reality. If you assume you can make that valve you assume you are no longer in reality… imho.
The springs/valve would
The springs/valve would create added resistance to the flow of the system. plus the water would be attempting to flow downwards and would increase in pressure as it was displaced by the balls. Plus as you run the generator you over time rob the system of energy. The reason no perpetual motion device works is because of this (the first law of thermodynamics):
http://www.grc.nasa.gov/WWW/k-12/airplane/thermo1f.html
" Within some problem domain, the amount of energy remains constant and energy is neither created nor destroyed. Energy can be converted from one form to another (potential energy can be converted to kinetic energy) but the total energy within the domain remains fixed."
The reason say; a gasoline engine works effeciently enough to be profitable is that all that energy is readily stored in the hydrocarbon bonds and lets you convert most of it to thermal and then to mechanical energy (and then if you wish to electrical). As you do this you remove energy from the gas and move it to your generator. Any generator works in this fashion. To have perpetual motion you would have to have a device with no friction and you could not remove any energy from the system. so theoretically if i found a patch of space somewhere with 0% gravity and somehow 0% fricition you still couldnt use it as a generator or you’d remove the power from the system.
That’s all gathered from a few quick checks with the web and what i remember from when we did ThermoDynamics in the AP Chemistry class last year…
Hope that makes more sense.
…
I dont think so the springs are supposed to open the door not close it also if the force from the spring its equal to the force of the water to the springs then only the force that makes the balls float its what it remains …
Springs inherently resist
Springs inherently resist motion… They are designed to compress or extend but will always try to return to their normal size.
That isnt the issue though. The water would still leak out unless it was water-tight. and if it was water-tight it would have a lot of friction.
If you look at some of the links i posted you can see that this sort of thing has been brought up before at other times and places. ITs a really nice idea but when you look at all the physics involved you realize that it cannot work.
for example this part is very key (from here):
“The usual texbook presentation of this considers only forces on the submerged object. The gravitational force mg acts downward. g is the size of the acceleration due to gravity. The buoyant force B acts upward. The net upward force is B - mg. From Archimedes’ principle, the size of B is B = r gV where r is the mass density of the liquid and V is the volume of the immersed body. This is correct, but it obscures the insight that when the immersed body moves up an equal volume of liquid must move down. Perpetual motion machine inventors very often forget to include that water motion in their thinking.”
And mogul FTW
…the weight of the water holding the ball down before it gets to a point where it can float --just as it enters. I think that just may be it.
I was quite impressed with the boy’s thinking on this one. I was even more impressed when I could not figure out why it would not work. To be honest, I knew in the back of my head that it wouldn’t --but gosh darn it, I could not see why.
Oh, I love fun little recreational thinking like this.
Your son is awesome!!!
…however, the system won’t work, and it’s not because of the valve - the valve could easily be built with a ferrofluid seal.
In order to understand why the system won’t work we need to imagine an equivalent system.
Let’s first focus on the balls and chain and think about what happens as the chain moves through the water. If you try to imagine the volume of water displaced by the balls at any time you will notice that it is practically constant, it actually varies around an average that is constant by, at most, half the volume of one ball.
So, let’s simplify our system and imagine that instead of a string with balls we have a rubber hose loop filled with air (with the ends of the hose connected togather). Can you see the reason why the system won’t work now?
The buoyant force is given by the resultant of all the pressure vectors. In the simplified system with the hose you basically have pressure pressing only perpendicular to the axis of the hose, there is no force pushing the hose up or down.
A tube that goes through the bottom of a vessel filled with water will not float away even though it is empty (filled with air).
You can easily test this yourself with a quick experiment. Take a vessel with a hole in the bottom (this could be a flower pot or half a plastic bottle with a hole drilled in the bottom) and a piece of PVC pipe (or any other pipe that fits in the vessel), put the pipe over the hole and pour water in the pot (between the pot and the pipe, not into the pipe). You will notice that the pipe won’t float away even though, the same pipe with its ends plugged would float.
I’ll try to make a drawing Phear my mad mspaint skillz!!!
Mad MsPaint Skills
You sir, do indeed have mad MsPaint skills. Fantastic diagram.
Talk about complicating things…
i think its a case of correct visualisation (a couple of you have hit on the points but your descriptions were over complicated)
imagine the following version of the experiment - not balls but a tube - even with a zero friction valve your brain knows instinctually that it will not revolve - it will remain stationary (even when the tube is segmented to follow the same physics laws as the balls)
gravity is only relevant here as it increases the density of the liquid via pressure from the rest of the water and all that air (people forget just how much air pressure we are under) thus affecting both halves of the air tube equally. the bit we forget is that lowering of the left side is moving the "bubbles" into higher density air.
i'll stop there as all the other mini details have been well and truelly covered
basically this wouldnt work on earth, in zero gravity or under zero pressure - everything just cancels itself out
cool idea tho - any kid that can confuse this number of nerds is gonna be very welcome in the fraternity
Dom
Great Visualization! I wont
Great Visualization! I wont bother then. I was about to make one showing the difference between a ball at the bottom of a tank of water and a ball underneath the container in this idea (surrounded largely by air). And show the difference between the forces but this is the simplest and cleanest way of explaining it.
Very nice simplification.
Yup
Your drawing perfectly illustrates what I was trying to say in my reply with the rubber hose loop.
Now people will start discrediting your drawing because if you go out swimming in the ocean you wouldn’t want to use an earthworm stuck through what looks like the cylindrical eyes of a blue-eyed robot
PS HTML needs a <sarcasm> tag.
The main problem with this machine…
…is that water will flow into the side with the oil when you make the hole into the dividing wall, not the other way around.
And this will happen until the pressure on the oil side equals the pressure on the water side.
The most awesome people ever!
Hey guys, I just wanted to drop a line here and give you guys a heads-up.
I am here! And I have been watching this thread like a hawk. I wanted to be sure you guys know that I have not been responding on purpose. Actually, there would be no point --each and every thing that I would bring up, has been brought up. Put simply, you guys are amazing.
I/we (me and Phee) decided (after seeing this go LMR-viral) that we should not “affect the results” by being part of the discussion. I really, really had some pre-conceived notions on this one, and I thought if I spoke up too much, I would end up steering the conversation one way or the other. In the end, I am glad we sorta stayed outta it. This thing has blossomed into an incredible conversation -and a wonderful though excercise. It has been more than a treat to watch this one go by.
Thank you, thank you,
Still lurking,
Chris