View Full Version : Pitch drop experiment
Handruin
09-04-2002, 12:25 PM
For those of you who read slashdot, you've probably seen this already, but I'm amused at this experiment so I wanted to share it.
The first Professor of Physics at the University of Queensland, Professor Thomas Parnell, began an experiment in 1927 to illustrate that everyday materials can exhibit quite surprising properties. The experiment demonstrates the fluidity and high viscosity of pitch, a derivative of tar once used for waterproofing boats. At room temperature pitch feels solid - even brittle - and can easily be shattered with a blow from a hammer (see the RealVideo® clip below). It's quite amazing then, to see that pitch at room temperature is actually fluid!
In 1927 Professor Parnell heated a sample of pitch and poured it into glass funnel with a sealed stem. Three years were allowed for the pitch to settle, and in 1930 the sealed stem was cut. From that date on the pitch has slowly dripped out of the funnel - so slowly that now, 72 years later, the eighth drop is only just about to fall.
They say no one has ever seen it drip... You can watch via the horrible realplayer if you have some spare time on your hands. :)
http://www.physics.uq.edu.au/pitchdrop/pitchdrop.shtml
Doug, that's a great little article. Thankyou!
flagreen
09-04-2002, 08:24 PM
Is there a point to this experiment? I mean is to find a way for insomniacs to get to sleep or what?
I've actually seen it in the flesh, as it were. :) It used to be in an entrance to one of the buildings, so you could press your nose to the glass and goggle if you wished.
It makes the prof's point very effectively, Bill. If someone told you that everyday materials that we take for granted were in fact liquids, it would be in one ear and out the other. To see it with your own eyes (normally impossible because it is just SO slow) really brings it home.
Things are not what they seem. :wink:
e_dawg
09-04-2002, 10:46 PM
Ice, as you know, also flows in glaciers.
The Grammar Police
09-04-2002, 11:21 PM
Interesting use of "as you know" there, Time. In this case, I guess the phrase ought to be "Ice, as you should know and actually already would know if you'd ever stopped to expend a synapse or two on the matter , also flows in glaciers". All of which is my way of saying "dunh - I knew that, just didn't think".
The Grammar Police
09-04-2002, 11:21 PM
Excuse me, E_dawg, not Time.
James
09-05-2002, 01:07 AM
Another one : Old glass windows are thicker at the bottom than at the top because glass is still a liquid.
The JoJo
09-05-2002, 02:50 AM
Ah, James, you beat me to it!
How quick do you have to be to beat the glass flowing out of your window pane?
(Sorry, JoJO, a cheap shot.)
Mercutio
09-05-2002, 08:57 AM
Just quibbling with James. (http://www.ualberta.ca/~bderksen/antique.html).
slo crostic
09-06-2002, 12:27 AM
On the topic of liquids, has anyone ever wondered why there are only two elements that remain liquid at room temperature?
And of these two, one is mercury (http://antoine.frostburg.edu/chem/senese/101/periodic/faq/why-is-mercury-liquid.shtml), which almost defies logic.
The other liquid I find strange is water. So dense it should be a solid....hhhhmmmm...what's going on there?
flagreen
09-06-2002, 01:16 AM
Water is an element? H2O isn't it?
flagreen
09-06-2002, 01:19 AM
Ooops! I may have done a bit of assuming there. I see now you didn't necessarily mean water was the other element which remained a fluid at room temperature. Sorry.
jtr1962
09-06-2002, 02:52 AM
A little food for thought-if glass was indeed also a supercooled liquid like pitch, then the glass funnel also would have dripped(or at least distorted) over the years. I heard a while ago that old window panes are distorted due to the manufacturing process, as that link by Mercutio mentions. If indeed glass really flowed, then the phenomenon should be measurable on modern windows over a period of a few years by using precision measurements of their thickness. To the best of my knowledge the glass holds its shape precisely, even in applications where millionths of an inch would be noticeable(i.e. large telescope mirrors and lenses).
Oh, glass becomes a liquid. According to one of those excellent articles that Mercutio linked to, all you need to do is have a nice warm room and plenty of paitence. You can see results (assuming you are using precision instruments) in as little as a few hundred years.
Ekaf-Ami
09-06-2002, 05:20 AM
Please excuse ignorant question of humble self, Miss Tea, madam, but what is your meaning of "nice warm room" exactly?
slo crostic
09-06-2002, 05:25 AM
To the best of my knowledge the glass holds its shape precisely, even in applications where millionths of an inch would be noticeable(i.e. large telescope mirrors and lenses).
Good point jtr, if glass was fluid all large telescope lenses would have to be replaced perioically. Imagine the logistics of renewing the lense in the hubble telescope :eekers:
You presume correctly flagreen, the other liquid element being bromine (http://education.jlab.org/itselemental/ele035.html) which appears to be a rather nasty substance.
Oooops! I should've said 'water should be a gas at room temperature' not a solid.
Anyway, check out this (http://witcombe.sbc.edu/water/chemistryproperties.html) site to see for yourself how 'weird' water really is.
Not at all, Mr Ekaf. In this context, "nice warm room" simply means that you need to keep the temperature somewhere over 270 degrees C. Or, if you are in a hurry and don't have 200-odd years to wait, then perhaps a little warmer. 500 degrees should do it nicely.
Ekaf-Ami
09-06-2002, 05:28 AM
Is also worthy of note that "water" is not "element". Even humble not-admitted-to-number-one-best-university student like me know that water is compound.
... if glass was fluid all large telescope lenses would have to be replaced perioically. Imagine the logistics of renewing the lense in the hubble telescope
I don't know about that. There is relatively little gravitational effect in an orbiting satellite. So even a normal liquid would flow extremely slowly without something to start it off.
My impression is that glass is a liquid with a structure too strong to flow at room temperature under normal gravity. Theoretically, if you increased the gravity enough (or made the piece of glass big enough), you should eventually see some sort of flow. Unfortunately, glass will shatter under its own weight well before then. :)
And we haven't even talked about liquid crystal yet, a substance supposedly caught between solid and liquid states?
e_dawg
09-06-2002, 07:21 AM
Oooops! I should've said 'water should be a gas at room temperature' not a solid.
So that means you the part where you said it was so dense was incorrect as well?
Anyways, I think one of the reasons why water remains a liquid when you would otherwise think it should be a gas is due to the polarity of the molecule. The hydrogen bonding that results probably keeps it together.
So that means you the part where you said it was so dense was incorrect as well?
Anyways, I think one of the reasons why water remains a liquid when you would otherwise think it should be a gas is due to the polarity of the molecule. The hydrogen bonding that results probably keeps it together.
Water is really freeky stuff, and even if logically it should be a gas it is still very dense... More dense than ice...
And that's definatly a polarity thing, although no actual bonding takes place the molecules are atracted to each other since the oxygen atom has a negative charge and the hydrogen atoms have positive charges, the way they are arranged puts the charges on oposite sides of the molecule.
Water could be viewed as both a positive and a negative ion depending on the angle, and can become either, hydroxy(OH) for example is the negative ion which found in pretty much all bases, and hydronium(H3O) is found in acids along with the hydrogen ion...
Water.... it's weird shit...
flagreen
09-06-2002, 07:44 AM
Is also worthy of note that "water" is not "element". Even humble not-admitted-to-number-one-best-university student like me know that water is compound.
Ekaf-Am'i,
I came across this new book by Jane Corbin and couldn't help but notice the striking resemblance between the picture on the cover and your portrait. Can you explain?
http://home1.gte.net/res0hopz/corbin.jpg
slo crostic
09-06-2002, 09:10 AM
Oooops! I should've said 'water should be a gas at room temperature' not a solid.
So that means you the part where you said it was so dense was incorrect as well?
That is the part I was refering to e_dawg. Perhaps I should've made myself more clear.
Another funny thing about water is that it is practically incompressible, or at least for all intents and purposes can be considered so.
btw, I definitely agree with you Sol, water is really weird shit.
Ekaf-Ami
09-06-2002, 11:19 AM
I came across this new book by Jane Corbin and couldn't help but notice the striking resemblance between the picture on the cover and your portrait. Can you explain?
http://home1.gte.net/res0hopz/corbin.jpg
Ahh, Mr Flagreen, sir, yes.
Person pictured on cover of your book is, in fact, self. Being full-time student in Madrid, and despite such small amounts of money as are sent to me by my mother in Bagdad (blessings be upon her), I am needful of income and am most kindly employed on irregular basis by photography studio as model. Perhaps one day I will be spotted by Hollywood Talent Scout and become Superstar of Silver Screen.
Or perhaps not.
You have seen famous British moviie by Mr David Lean - Laurence of Arabia? Perhaps you recall scene where Laurence (Mr Peter O'Toole) meeting with Sherif Ali (Omar Sharif) for first time? My great mother (great mother? mother of my mother - I am sometime unsure of correct English) is accessory to that famous scene. (Third camel from left.)
Clocker
09-06-2002, 03:54 PM
It is true...glass is actually liquid.
Mustafa Hussein
09-06-2002, 05:40 PM
Ekaf? My nef-you! How is your mother? Why peeple not friendly here? They no like arab?
Mustafa Hussein
09-06-2002, 05:42 PM
It is true...glass is actually liquid.
Stupid American! Glass liguid?!? Haaaaa.....
SteveC
09-06-2002, 06:21 PM
Ekaf? My nef-you! How is your mother? Why peeple not friendly here? They no like arab?
Not friendly? We built you an 18,000 hole golf course in 1991. You didn't like it? We're planning on building you another one in a few months. It's a gift from all Americans to your leader.
Steve
Mustafa Hussein
09-06-2002, 06:35 PM
Ekaf? My nef-you! How is your mother? Why peeple not friendly here? They no like arab?
Not friendly? We built you an 18,000 hole golf course in 1991. You didn't like it? We're planning on building you another one in a few months. It's a gift from all Americans to your leader.
Steve
Ahh.. now Mustafa see. Big boom boom ha? Goats run, Mustafa run, tent no run. Goats ok, Mustafa ok, tent gone. You buy Mustafa new tent? Mustafa like America. Go Jets right? go George Bush. See Mustafa like America. New tent ok? You buy?
NRG = mc²
09-06-2002, 08:42 PM
LOL @ Mustafa
Mustafa Hussein
09-06-2002, 08:46 PM
LOL @ Mustafa
Hey you person. You like goats?
Mustafa Hussein
09-06-2002, 08:48 PM
Here's my favortie.
You like?
NRG = mc²
09-06-2002, 09:02 PM
Very nice mustafa my friend.
But what to do with goats? I think know what you person likes to do with goats they say but I don't'. Filthi busterd.
Mustafa Hussein
09-06-2002, 09:16 PM
Very nice mustafa my friend.
But what to do with goats? I think know what you person likes to do with goats they say but I don't'. Filthi busterd.
What to do with goats? You nuts? Goats for mother's milk. For kabobs. Good. Muatafa very proud of goats. Now Mustafa's nefyou Ekaf-Ami, he has own ideas. One time when American and British drop boom boom, Mustafa rent truck to move goat herd to mountains for safe. Mustafa's brother Hosni went to town and get it. He bring truck back where goats, Mustafa, and Ekaf-Ami wait. Planes come. Boom boom all around. Ekaf get scared. Goats get scared. Mustafa get scared. Hosni say "get goats in truck quick!". Mustafa jump in truck instead and say "Screw the goats! We go!". Ekaf-Ami say "You think we have time?". What you gonna do with nefyou like that?
Any word on what Sheik Yerbouti has been up to lately?
http://gs.cdnow.com/graphics/COVERART/local/L/40/95/00004095.jpg
Mustafa Hussein
09-07-2002, 04:50 AM
One such as he is not spoken of. His greatness forbids it. Mustafa is but humble goat herder.
Look, Mouse-stuffer, I don't care if your house is sane. Just take your goats and your bestial nephew and clear off! Otherwise you'll go home to your Dad in a bag. :bibber:
Explorer
09-07-2002, 10:22 AM
Water is really freeky stuff, and even if logically it should be a gas it is still very dense... More dense than ice...
Keyword: Phase
Liquid water is denser than solid water (ice) because hydrogen hydroxide (HOH, H2O) expands as it enters its solid phase -- which defies the norms of all other molecules. Water at a temperature of somewhere about 1.5ºC ~ 2ºC is found at the bottoms of deep fresh water lakes in cold climates because water at this temperature is at its highest density, and the colder ice is found floating on top of the lake.
Mustafa Hussein
09-07-2002, 11:21 AM
Look, Mouse-stuffer, I don't care if your house is sane. Just take your goats and your bestial nephew and clear off! Otherwise you'll go home to your Dad in a bag. :bibber:
Oh you real tough guy huh?
Stereodude
09-07-2002, 04:51 PM
Water is really freeky stuff, and even if logically it should be a gas it is still very dense... More dense than ice...
Keyword: Phase
Liquid water is denser than solid water (ice) because hydrogen hydroxide (HOH, H2O) expands as it enters its solid phase -- which defies the norms of all other molecules. Water at a temperature of somewhere about 1.5ºC ~ 2ºC is found at the bottoms of deep fresh water lakes in cold climates because water at this temperature is at its highest density, and the colder ice is found floating on top of the lake.
I'ts probably a good thing too, or else all the fishies and anything else in lakes would get frozen and be dead in the winter.
Stereodude
James
09-08-2002, 06:00 AM
Just quibbling with James. (http://www.ualberta.ca/~bderksen/antique.html).
Thanks Merc. It's a fair cop. :mrgrn:
slo crostic
09-08-2002, 06:59 AM
It is also interesting to note the atmospheric pressure/boiling point issue with water.
At sea level water boils at 100C (213F) but when elevated to 3050M (10,000ft) it boils at 90C (193F) although I suspect this would also be the case with other liquids/gases.
jtr1962
09-08-2002, 07:21 AM
It is also interesting to note the atmospheric pressure/boiling point issue with water.
At sea level water boils at 100C (213F) but when elevated to 3050M (10,000ft) it boils at 90C (193F) although I suspect this would also be the case with other liquids/gases.
Yes, indeed it is. Boiling point is the point at which the vapor pressure of the liquid exceeds the pressure of the surrounding environment. As you raise the temperature of a liquid the vapor pressure goes up, and the temperature at which the vapor pressure exceeds the ambient air pressure is what is commonly referred to as the boiling point. Naturally, at higher altitudes the air pressure is less, so the boiling point is lower. Water at room temperature has a vapor pressure of 0.3 psi(normal atmospheric pressure is 14.7 psi). This means water at room temperature will boil at approximate 100,000 feet altitude, and in a complete vacuum liquid water(or any liquid) will boil at any temperature(unless it is frozen solid). This is why materials used for lubrication is outer space must be solid(i.e. Teflon). Any greases will eventually vaporize(or outgas as the phenomenon is usually called).
Explorer
09-10-2002, 07:32 AM
'ts probably a good thing too, or else all the fishies and anything else in lakes would get frozen and be dead in the winter...
Since you're in Michigan, ever notice how most lakes during the beginning of winter start "churning?" That's the displaced water coming up to the surface, getting chilled and becoming more dense, then going back down towards the bottom and displacing slightly warmer water which comes to the surface to be chilled... etc.
BTW, ever see goldfish "frozen in place" in a pond in the wintertime, just to see the same ones swimming around like nothing happened later on in spring? Kinda weird.
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