pendulum waves

[velkyn]

I debated on putting this here or in "science"

hypmotized!

No sound


music

[Argyle]

Isn't the mathematics of wavelengths fantastic? 

[Nick]

Better be careful...you could be messing around with demon stuff.

[Argyle]

Maybe I am inspired by demons to love science I should repent so I can go back to being safe from demons who want me not to be ignorant.

[velkyn]

demons eh?  rather not the knife wielding ones that Christians seem to want to invoke.



whoever "brusspup" is, they have lots of neat videos. 

[velkyn]

not waves but optical illusion that you just have to see by brusspup

[Omen]

What a fantastic example of self organization.

http://en.wikipedia.org/wiki/Self-organization

[RNS]

nice stuff. that last one reminds me of this one:

[Argyle]

They use that same optical illusion in the haunted house at DisneyLand.

[Poseidon]

That pendulum thingy is a swinging toy. Pun intended.

It is said that Galileo first observed and pondered pendulum action while in church.Someone had bumped the chandelier while lighting the candles.  The light fixture swung from side to side in pendulum mode. Galileo, not paying attention to the church service began to wonder about the physics of the situation. He timed the period of swings by using his pulse as a measure.

Jean Foucalt, the old french physicist used a pendulum along with a flat plate inscibed with markings similar to a compass rose. He observed that the pendulum not only swung to and fro but also in a very slow, small, circle. That experiment became physical evidence that the earth is rotating.

Velkyn had told us that she is a geologist. SHe will be familiar with the pendulum device used by past geologists to discover oil deposits. Their pendulum device would have a longer interval time when over an oil cavity.

The period of oscillation is unaffected by the mass of the bob weight. Nor is it affected by the width of the arc that it swings through. The only variables that affect period time is the length of the string and the acceleration og gravity (g). The factor g is normally taken to be 32 when calculated with the imperial system. To find the period of oscillation we can use the following formula.............Two times pi times the square root of L diviided by g.  L is the length of the pendulum string.  You can see that if either L or g is changed, then the swing period will change. That is what makes that fascinating pendulum video work. QUite simply, the varying length of the strings cause the swing periods to be different. Thinking of it in a different but still valid way, the speed of the balls is different from each of its neighbors.

To be sure that Brusspup guy is clever and probably a knowledgeable physics practitioner.

[nogodsforme]

not waves but optical illusion that you just have to see by brusspup

That dragon was crazy scary cool. A real Freakazoidasaurus!

[velkyn]

we used to have a very nifty pendulum in the science building at my university.  bad thing was that they roof leaked and screwed up the mechanism at the top. 

Pos, I wasn't aware that people actually used pendulums to find oil deposits with actual science. I know plenty of dowers have used them, even over maps.   

[Poseidon]

Vel; I doubt that oil exploration crews use pendulums any more. There are far more sophisticated methods available these days. They were used in the past and yes they worked. It was not like a dousing rod or any of that hokum.

 Here is the reason that it will work over a substantial deposit. The mass density of the earth is slightly lower at a location with a big cavity filled with crude. That means that the acceleration of gravity, g =32, is somewhat lower. Now look at the pendulum equation. The factor , g, is a denominator for L. The quotient is under the radical. Change g either way and you get a different swing period. Those old geology folks were pretty clever even though the available methods were what we would now label primitive.

[velkyn]

I just think it would have been damn hard to have clocks sensitive enough to get the information you needed.  But amazing what our ancestors did without such things as transistors and chips      hmmm, I think that aliens told the oil explorers where the deposits were!  That's it!  and now I need to scare my hair so I look like some of those nitwits on Ancient Aliens.

[Poseidon]

C'mon Vel you are a plenty bright lady. We have had very accurate time pieces for a hundred years. When timing the swing of a pendulum you would not count only one swing but many. If the pendulum period, determined by the length of the string, was say 2.0 seconds that would be hard to resolve into hundredths of a second. But count and time 30 or 50 swings and the time becomes 60 seconds or 100 seconds. Not so hard to discriminate small variations now.

P.S. when you run out of sciency things to study, look up the history of chronographs. Fascinating stuff. Accurate timepieces were extremely important to those navigators who wanted to, needed desperately to, determine longitude. The crown of England offered a big time cash reward to the person who developed a relianble timepiece that could be used reliably by sea navigators. Old time railroaders used to brag about the accuracy of their watches more proudly than  bragging about the dimensions of their phallus, Even Dagny Taggert (Atlas Shrugged) knew that. You're forgiven cause you ain't old enough to remember that kind of ancient trivia.

[velkyn]

well, it works so who I am to argue.  I find that it is hard to fathom (yep, a personal incredulity fallacy  ) that one can determine the 0.01% or smaller variation of gravity which I do find different than a few miles here or there in early navigation, but as you described it can be done with time.  I found this which I thought was good: http://www.earthsci.unimelb.edu.au/ES304/MODULES/GRAV/NOTES/pend.html 

and I do have to be embarassed or at least shocked because I don't recall this being taught at *all* to me in any of my geology courses or physics.   

[Poseidon]

Hey, there's another nifty information source from your seemingly boundless supply. Those Aussies are not invariably about koala bears and Fosters beer, some of 'em are plenty smart. Thanks for the referral.