Properties of water - what's the effect here?

tommodmc · 14th March 2008, 11:08 PM

Get a steady, strong stream of water from a tap. Get a pencil or something, move it slowly closer to the stream of water [along the side, not a point but a curvature]. Notice how the water adheres to the object, attracted to it without even touching, no matter the force of the water coming down?

What the hell are the effects working here?

TaO! · 14th March 2008, 11:29 PM

Anything with a sufficiently strong magnetic field will interact with dipole molecules like water. You'll probably get a better bend in a stream of water with a sufficiently charged balloon or comb.

brokenback · 14th March 2008, 11:32 PM

H2O is a polar molecule..... It has a charge not evenly distributed across the molecule and is thus called polar. Running H2O it past the pencil, which I assume also has a charge, causes it to attract or repel the polar molecule.

avandonk · 15th March 2008, 10:37 AM

Venturi effect

Bert

Assasinator_2 · 15th March 2008, 1:32 PM

Quote:

Originally Posted by avandonk

Venturi effect

What the fuck? You're crazy and have no clue.

Static electricity builds up on the pencil (als: builds up on glass rods if you rub them with cloth, etc). Because water is H2O, which is in the shape of a triangle, you have the H on one side, and the 2 O's on the other. Because O ion is O2- and H is H+, you get a slight positive charge on one side, and a slight negative on the other. As such, you get magnetic attraction doing its thing, and the water stream bends towards the pencil/rod/whatnot.

brokenback · 15th March 2008, 1:55 PM

Quote:

Originally Posted by Assasinator_2

What the fuck? You're crazy and have no clue..

If it is who I think it is posting (Bert from IIS)....then they he is defiantly not crazy!

But I would love to hear more!

stewpot · 15th March 2008, 3:30 PM

The Venturi effect drags the water stream close to the object, because the moving water drags along a stream of air as well. Once the water touches the object the Coanda effect takes over. Wikipedia link.

Back when electronics were fragile, fluidic logic circuits were built using flows of air instead of flows of electrons. Flip-flops, which are single bit storage units, used the Coanda effect to store a bit. Back when I was a young tacker, I used to wonder how large a calculator would be if it was built from fluidic components, how much air it would use, and how awesome it would be. I was a nerd.

Bastard Child · 15th March 2008, 7:30 PM

I thought coanda was for fluid in contact, and the opening post was "without even touching"?

tommodmc · 16th March 2008, 1:42 AM

Quote:

Originally Posted by Bastard Child

I thought coanda was for fluid in contact, and the opening post was "without even touching"?

Includes when they touch as well.

Bennys4mg · 16th March 2008, 2:55 AM

Quote:

Originally Posted by Assasinator_2

H on one side, and the 2 O's on the other.

HO2? wow.. water is now an ion HO2---?

its static electricity that attracts the water, use an ebonite rod and you'll get the reverse effect. Same effect as rubbing a comb on your woolen jumper and picking up pieces of paper.

Munkiboy · 16th March 2008, 8:41 AM

Quote:

Originally Posted by Assasinator_2

What the fuck? You're crazy and have no clue.

Static electricity builds up on the pencil (als: builds up on glass rods if you rub them with cloth, etc). Because water is H2O, which is in the shape of a triangle, you have the H on one side, and the 2 O's on the other. Because O ion is O2- and H is H+, you get a slight positive charge on one side, and a slight negative on the other. As such, you get magnetic attraction doing its thing, and the water stream bends towards the pencil/rod/whatnot.

Quote:

Originally Posted by stewpot

The Venturi effect drags the water stream close to the object, because the moving water drags along a stream of air as well. Once the water touches the object the Coanda effect takes over. Wikipedia link.

way to totally pwn urself. and way to potentially drive away a very intelligent and constructive member of the community in avondonk. i found this interesting, i had forgotten about the venturi effect *doffs hat to those in teh know*

brokenback · 16th March 2008, 10:10 AM

Yeah but, Bert didn't really elaborate thus his statement was difficult for most people to understand why.

Assasinator_2 · 16th March 2008, 10:19 AM

Quote:

Originally Posted by Bennys4mg

HO2? wow.. water is now an ion HO2---?

its static electricity that attracts the water, use an ebonite rod and you'll get the reverse effect. Same effect as rubbing a comb on your woolen jumper and picking up pieces of paper.

Yup. My bad. I meant H2O

It's pretty clear in that how I stated O2- and H+ - I screwed up the order where you quoted whoops!

Quote:

Originally Posted by Munkiboy

way to totally pwn urself. and way to potentially drive away a very intelligent and constructive member of the community in avondonk. i found this interesting, i had forgotten about the venturi effect *doffs hat to those in teh know*

We had been specifically stated in the OP that it was a rod - in this case, a pencil. It's completely to do with the dipole properties of water and the fact that a charged rod (glass, pencil, whatnot) produces electromagnetic attraction. Read this.

Here is a video that shows this exact principle happening, with the charge buildup being used to arc two terminals. Here are more sources discussing the electrostatic attraction principle.

The effect quoted that you're claiming is responsible involves a spoon or other object shaped like that, not a pencil or rod or whatnot. The pencil comes form electrostatic charge. The spoon has the effect of acting like a diverging nozzle, in which case you'd be right, but we were specifically talking about a long rod (in this case a pencil).

edit: To clarify - I know that the venturi effect can have a role here and that the people claiming so are technically right, but this experiment is the textbook demonstration of water's dipole properties when done with a glass rod or pencil. It's highly likely that from a pencil, the dominating factor that will influence the curvature of water will be electrostatic attraction.

tommodmc · 16th March 2008, 12:02 PM

It's possible that the same effect is achieved by a different means on a charged pencil, but the same effect also exists on a curved anything such as finger, spoon, etc.

Two reasons and scenarios for the same phenomena, both answering my question. Thank you.

14th March 2008, 11:08 PM	#1
tommodmc Member Join Date: Aug 2007 Posts: 544	Properties of water - what's the effect here? Get a steady, strong stream of water from a tap. Get a pencil or something, move it slowly closer to the stream of water [along the side, not a point but a curvature]. Notice how the water adheres to the object, attracted to it without even touching, no matter the force of the water coming down? What the hell are the effects working here?

14th March 2008, 11:29 PM	#2
TaO! Member Join Date: Feb 2004 Location: Fremantle Posts: 792	Anything with a sufficiently strong magnetic field will interact with dipole molecules like water. You'll probably get a better bend in a stream of water with a sufficiently charged balloon or comb. __________________ "If we knew what it was we were doing, it would not be called research, would it?" -- Einstein.

15th March 2008, 10:37 AM	#4
avandonk Member Join Date: Jul 2003 Location: Melbourne the local universe Posts: 386	Venturi effect Bert __________________ avandonk

15th March 2008, 3:30 PM	#7
stewpot Member Join Date: Sep 2001 Location: NW Tas Posts: 1,165	The Venturi effect drags the water stream close to the object, because the moving water drags along a stream of air as well. Once the water touches the object the Coanda effect takes over. Wikipedia link. Back when electronics were fragile, fluidic logic circuits were built using flows of air instead of flows of electrons. Flip-flops, which are single bit storage units, used the Coanda effect to store a bit. Back when I was a young tacker, I used to wonder how large a calculator would be if it was built from fluidic components, how much air it would use, and how awesome it would be. I was a nerd. __________________ FOLDING LIKE A MOFO ============ TRADING HISTORY ============ COMIC SANS GETS ME HOT Last edited by stewpot; 15th March 2008 at 3:33 PM.

14th March 2008, 11:32 PM	#3
brokenback Member Join Date: Jun 2001 Location: Melbournia, Arsetralia Posts: 1,245	H2O is a polar molecule..... It has a charge not evenly distributed across the molecule and is thus called polar. Running H2O it past the pencil, which I assume also has a charge, causes it to attract or repel the polar molecule.

15th March 2008, 7:30 PM	#8
Bastard Child Member Join Date: Jan 2006 Location: Crooklyn 3012 Posts: 2,063	I thought coanda was for fluid in contact, and the opening post was "without even touching"?

16th March 2008, 10:10 AM	#12
brokenback Member Join Date: Jun 2001 Location: Melbournia, Arsetralia Posts: 1,245	Yeah but, Bert didn't really elaborate thus his statement was difficult for most people to understand why.

16th March 2008, 12:02 PM	#14
tommodmc Member Join Date: Aug 2007 Posts: 544	It's possible that the same effect is achieved by a different means on a charged pencil, but the same effect also exists on a curved anything such as finger, spoon, etc. Two reasons and scenarios for the same phenomena, both answering my question. Thank you.