• Hi Guest: Welcome to TRIBE, the online home of TRIBE MAGAZINE. If you'd like to post here, or reply to existing posts on TRIBE, you first have to register. Join us!

The Pitch Drop Experiment

PosTMOd

Well-Known TRIBEr


http://www.physics.uq.edu.au/pitchdrop/pitchdrop.shtml

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 video 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 a 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.

The experiment was set up as a demonstration and is not kept under special environmental conditions (it is actually kept in a display cabinet in the foyer of the Department), so the rate of flow of the pitch varies with seasonal changes in temperature. Nonetheless, it is possible to make an estimate of the viscosity of this sample of pitch (R. Edgeworth, B.J. Dalton and T. Parnell, Eur. J. Phys (1984) 198-200). It turns out to be about 100 billion times more viscous than water!




Pitch, before and after being hit with a hammer:
 

PosTMOd

Well-Known TRIBEr
1927 Experiment set up
1930 The stem was cut
December 1938 1st drop fell
February 1947 2nd drop fell
April 1954 3rd drop fell
May 1962 4th drop fell
August 1970 5th drop fell
April 1979 6th drop fell
July 1988 7th drop fell
November 28, 2000 8th drop fell
 
tribe cannabis accessories silver grinders

PosTMOd

Well-Known TRIBEr
They had a webcam, but there's been technical difficulties apparently... until they fix them, we are in the dark... the pitch dark...
 

PosTMOd

Well-Known TRIBEr
AdRiaN said:
How does that compare to molasses in January?
Pitch it again to me in January and I'll tell you. And I know you won't be the only one, so I will empty my PM box now in wonderful anticipation.
 

NemIsis

TRIBE Member
seeker said:
only still photos? we're in the 21st century, dammit. i can't believe there's no webcam.
Considering it seems to takes about 7-9 years for it to drop, what would be the point??
 
tribe cannabis goldsmith - gold cannabis accessories

dvs

TRIBE Promoter
regarding the professor's note... it would be a bitch but from a purist/control standpoint shouldn't they start the experiment over [with temp control] for precise meaurements from a beaker height that wouldn't allow the drop to be impeded?
 

PosTMOd

Well-Known TRIBEr
dvs said:
regarding the professor's note... it would be a bitch but from a purist/control standpoint shouldn't they start the experiment over [with temp control] for precise meaurements from a beaker height that wouldn't allow the drop to be impeded?
I think they made their point regardless.


pitchincoldsnap:molassesinheatwave::normalthought:somewhatbetterthought
 

nusty

TRIBE Member
possibledj said:
for those days when there's NOTHING on.
on those days I think I would tune to the weather network first....


*nick, have you forwarded this to Max yet? or should I?
 
Top