@theSolarisDragon That's not 100% clear as I haven't seen the experiment done. It was done a long time ago and reported that it worked (there are several old papers in the literature). I'm rather keen to try it, I just need to find the time. If I do, I will definitely catch it on video.
@micolich If it does work in a vacuum it would indicate that Dr Hughes is in part right, but only under those conditions. It would be interesting to see the outcome.
@theSolarisDragon Steady on a second, its not that simple. What if there's a limit to the height that the siphon can run to, one that then ends up being dependent on atmospheric pressure, and I don't mean the Earth's atmosphere, I mean the pressure of the atmosphere above the liquid in the reservoirs. A vacuum is not perfect, nor is it an all or nothing thing. Science isn't a yes or no, right or wrong game, there's much more to it.
@micolich Yes I agree, it would not be possible to conclusively determine it, unless the experiment could be done in a perfect vacuum, but what I was saying was that if the it was possible to siphon in a very low pressure vacuum it would give an indication of what drives the siphoning - pressure or hydrogen-bond chain. I may not have done a comparable amount of science as you, but I think you would agree that it is not unreasonable to form a hypothesis prior to an experiment .
@theSolarisDragon No problems with forming a hypothesis, that's good science. Conclusions are another story. Personally, I don't believe this hydrogen bond chain hypothesis, because if it was true, it would work if you just had a little semicircular channel to have the water flow through. You need a closed sealed tube for a siphon to work and even a small hole in it is enough to make it not work. Leaks being a problem are a classic hallmark of pressure playing a vital role.
@micolich : Don't bother with some youtube comments. A hint is given here : xkcd.com/202/
This is interesting. I was tempted to believe straightforwards the theory of the Queensland university because I had seen a siphoning of a chain (sort of : a long collar). It is true that hydrogen bonds are not that strong...
@stegre Did I say that it didnt? I'm sorry that you have such little self-worth that you feel the need to berate me with offensive language in order to inflate your own ego. Why don't you contribute something positive to the world, you might feel better about yourself.
1 You have misquoted Dr Hughes in the first paragraph,
2 You may have misunderstood what he means by the importance of the hydrogen bond. The hydrogen bond keeps the column of water on the down side together, keeping the column largely intact so it can pull the water in the other column up.
3 The atmospheric pressure on the upper side is practically equal (p=ρgh) to the atmospheric pressure on the lower side. Therefore with the pressures being equal, atmospheric pressure cannot be a factor.
@gm255 First, please fact check your accusations first. I make two quotes in the video. The first is a direct quote of Hughes' words taken from an article on the PhysOrg website. I checked this quote was correct by going to the QUT news website and viewing the actual news release that Hughes' must have agreed to before his university's media office posted it. The second is taken directly (and verbatim) from his own paper in Physics Education.
"Dr Stephen Hughes at Queensland University of Technology proposes that the fact that gravity is involved is a common misconception..... ."."
From the QUT website
"Dr Hughes said the Oxford English Dictionary (OED) since 1911 had incorrectly stated that atmospheric pressure was the operating force in a siphon when in fact it was gravity."
@gm255 Regarding point 2: I understand entirely what he means, and I believe it is incorrect. I think my first experiment conclusively shows that the water on the 'down-side' is not pulling the water on the 'up-side'.
If you disagree, then try this experiment. Cut a slit along the entire length of the tube (or make an open canal for the water that runs up from the upper reservoir and then down to the lower one) , if its water pulling water, then the siphon should still work. I bet it doesn't.
I think the air bubble volume increases and its pressure reduces, again this pressure difference, brought about by the downward flowing column of water. causes the water to be sucked up into the tube.
I'm not sure what you mean here about cutting it. Would the slit not just make it an open channel. Then thats not closed, so its not a siphon any more?
@gm255 Finally, regarding point 3: In this special case, the atmospheric pressure is a factor, it just cancels to zero (more precisely, becomes negligible). Imagine we had an atmosphere with a scale height of 8.5m rather than 8500m (the height over which the pressure drops by a factor of 1/e). Then I can assure you, atmospheric pressure is certainly a factor.
My central point remains the same. To correctly describe a siphon in general one needs to include BOTH pressure AND gravity.
@gm255 Even here on earth, including atmospheric pressure in the equations is absolutely vital. The maximum height that your siphon can raise water up above the upper reservoir is around 10m (see a future video), and that is set by atmospheric pressure. Throw such apparently irrelevant terms out and you can no longer explain why this is so.
@gm255 If both ends are at atmospheric pressure then atmospheric pressure doesn't drive it, but I never said that it does. But, it is wrong to then infer that atmospheric pressure is completely irrelevant to the siphon's operation as a general condition, and that is the point that I'm making with this video.
Excellent
nelsongast1 8 months ago
excellent videos.
kimikozembower 8 months ago
An excellent demonstration. Thank you.
ariejudy 9 months ago
Comment removed
theSolarisDragon 9 months ago
What happens if this experiment is conducted in a vacuum?
theSolarisDragon 9 months ago
@theSolarisDragon That's not 100% clear as I haven't seen the experiment done. It was done a long time ago and reported that it worked (there are several old papers in the literature). I'm rather keen to try it, I just need to find the time. If I do, I will definitely catch it on video.
micolich 9 months ago
@micolich If it does work in a vacuum it would indicate that Dr Hughes is in part right, but only under those conditions. It would be interesting to see the outcome.
theSolarisDragon 9 months ago
@theSolarisDragon Steady on a second, its not that simple. What if there's a limit to the height that the siphon can run to, one that then ends up being dependent on atmospheric pressure, and I don't mean the Earth's atmosphere, I mean the pressure of the atmosphere above the liquid in the reservoirs. A vacuum is not perfect, nor is it an all or nothing thing. Science isn't a yes or no, right or wrong game, there's much more to it.
micolich 9 months ago
@micolich Yes I agree, it would not be possible to conclusively determine it, unless the experiment could be done in a perfect vacuum, but what I was saying was that if the it was possible to siphon in a very low pressure vacuum it would give an indication of what drives the siphoning - pressure or hydrogen-bond chain. I may not have done a comparable amount of science as you, but I think you would agree that it is not unreasonable to form a hypothesis prior to an experiment .
theSolarisDragon 9 months ago
@theSolarisDragon No problems with forming a hypothesis, that's good science. Conclusions are another story. Personally, I don't believe this hydrogen bond chain hypothesis, because if it was true, it would work if you just had a little semicircular channel to have the water flow through. You need a closed sealed tube for a siphon to work and even a small hole in it is enough to make it not work. Leaks being a problem are a classic hallmark of pressure playing a vital role.
micolich 9 months ago
@micolich : Don't bother with some youtube comments. A hint is given here : xkcd.com/202/
This is interesting. I was tempted to believe straightforwards the theory of the Queensland university because I had seen a siphoning of a chain (sort of : a long collar). It is true that hydrogen bonds are not that strong...
Newtoon 1 year ago
gravity drives atmospheric pressure too, asshole!
stegre 1 year ago
@stegre Did I say that it didnt? I'm sorry that you have such little self-worth that you feel the need to berate me with offensive language in order to inflate your own ego. Why don't you contribute something positive to the world, you might feel better about yourself.
micolich 1 year ago
Great explanation! Now excuse me while i go pee...
Etni3s 1 year ago
@Etni3s :)
micolich 1 year ago
Comment removed
Newtoon 1 year ago
1 You have misquoted Dr Hughes in the first paragraph,
2 You may have misunderstood what he means by the importance of the hydrogen bond. The hydrogen bond keeps the column of water on the down side together, keeping the column largely intact so it can pull the water in the other column up.
3 The atmospheric pressure on the upper side is practically equal (p=ρgh) to the atmospheric pressure on the lower side. Therefore with the pressures being equal, atmospheric pressure cannot be a factor.
gm255 1 year ago
@gm255 First, please fact check your accusations first. I make two quotes in the video. The first is a direct quote of Hughes' words taken from an article on the PhysOrg website. I checked this quote was correct by going to the QUT news website and viewing the actual news release that Hughes' must have agreed to before his university's media office posted it. The second is taken directly (and verbatim) from his own paper in Physics Education.
These are direct, accurate quotes.
micolich 1 year ago
@micolich
Hi micolich,
From your first paragaph.
"Dr Stephen Hughes at Queensland University of Technology proposes that the fact that gravity is involved is a common misconception..... ."."
From the QUT website
"Dr Hughes said the Oxford English Dictionary (OED) since 1911 had incorrectly stated that atmospheric pressure was the operating force in a siphon when in fact it was gravity."
gm255 1 year ago
@gm255 Regarding point 2: I understand entirely what he means, and I believe it is incorrect. I think my first experiment conclusively shows that the water on the 'down-side' is not pulling the water on the 'up-side'.
If you disagree, then try this experiment. Cut a slit along the entire length of the tube (or make an open canal for the water that runs up from the upper reservoir and then down to the lower one) , if its water pulling water, then the siphon should still work. I bet it doesn't.
micolich 1 year ago
@micolich
I think the air bubble volume increases and its pressure reduces, again this pressure difference, brought about by the downward flowing column of water. causes the water to be sucked up into the tube.
I'm not sure what you mean here about cutting it. Would the slit not just make it an open channel. Then thats not closed, so its not a siphon any more?
gm255 1 year ago
@gm255 Finally, regarding point 3: In this special case, the atmospheric pressure is a factor, it just cancels to zero (more precisely, becomes negligible). Imagine we had an atmosphere with a scale height of 8.5m rather than 8500m (the height over which the pressure drops by a factor of 1/e). Then I can assure you, atmospheric pressure is certainly a factor.
My central point remains the same. To correctly describe a siphon in general one needs to include BOTH pressure AND gravity.
micolich 1 year ago
@micolich
If its zero or negligible, then thats "not a factor" surely?
OK I guess you are right to include the atmospheric term for completeness? Is that what you mean?
But, I am thinking about here on earth, so it is zero...practically.
gm255 1 year ago
@gm255 Even here on earth, including atmospheric pressure in the equations is absolutely vital. The maximum height that your siphon can raise water up above the upper reservoir is around 10m (see a future video), and that is set by atmospheric pressure. Throw such apparently irrelevant terms out and you can no longer explain why this is so.
micolich 1 year ago
Sorry....gravity, or more correctly, the pressure difference between the fluid levels is the power behind a siphon.
If both ends are at atmospheric pressure, then no pressure differential exists, so how can atmospheric pressure drive it?
P = rho g h.......so its the h of the column of fluid (difference between fluid levels) that causes the pressure differential and hence flow.
Even with the air bubble, the water still siphons as there is still a pressure differential, causing flow.
gm255 1 year ago
@gm255 If both ends are at atmospheric pressure then atmospheric pressure doesn't drive it, but I never said that it does. But, it is wrong to then infer that atmospheric pressure is completely irrelevant to the siphon's operation as a general condition, and that is the point that I'm making with this video.
micolich 1 year ago
@micolich
Well, from your third paragraph I thought you do say just that.
"Together, these show that a mixture of gravity and atmospheric pressure drive the siphon,........"
gm255 1 year ago
Not sure what the ring is, but I was trying a new set-up, and it might be connected to that. I'll look into it.
And the plastic tubes, try any hardware store.
micolich 1 year ago
Very cool... 2 things:
What is with that high frequency ring throughout the video? And
Where can I get some of those plastic tubes...?
XTrumpet63X 1 year ago
I thought that hydrogen bond explanation sounded fishy considering the siphon's infamy for moving hydrocarbons out of fuel tanks. :-)
CousinoMacul 1 year ago
Absolutely correct. I'm amazed how all the dictionaries and encyclopedias will now carry an incorrect definition.
supermaucat 1 year ago
Very cool, glad to see you're back making videos. After watching the video I spent the past hour researching siphons :)
cryotwin 1 year ago