microbiotic farts.

anrothar

entirely thrilled
if you pour a beer into a glass, and hold the glass up in front of you, moving it side to side, you will notice that the bubbles ascend on an angle in the direction that you are moving the glass. ie: if you are moving the glass to the right, they will ascend slightly to the right. it makes sense when you think about it, but it's neat to see. visually, it would seem like it should go the oppositte way, but logically, it's right on. mass, density, and all that stuff. i'm sure brad can give us a scientific explanation....
 
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SpartaBard

Well-Known Member
Team MTBNJ Halter's
Yeah, it is the same principle by which an accelerometer works, basically the bubbles are less dense than the beer and as you move the glass to the left, the beer has a tendency to stay in place on the right, due to its inertia, the bubbles will be forced to the left. In a basic physics class one would use a jar of vegetable oil and a cork stopper.

When you slow down or stop the motion the bubble should move backwards (moving the glass to the left and stopping will make the bubbles initially move left and as you stop, they will move towards the right showing a negative acceleration.
 
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DANSPANK

Guest
May I interject? Thanks. Now is the movement mere appearance or are the bubbles actually following the movement of the glass? If the bubbles are, in fact, moving the same direction as the glass then they would have to generate acceleration from somewhere - they would have to be moving to the left faster than the glass to actually be moving to the left as opposed to simply rising vertically within the glass yet seemingly moving to the left as you see it from an enablers point-of-view.

Hmmmmmm.... If I had a long beard I would be stroking it and pondering this right now. Sadly I only have a cup of tea in front of me so me immediate research is hindered by both the viscosity of the tasty breakfast brew and the visually impenetrable red drinking vessel.
 

anrothar

entirely thrilled
since the liquid is in a tall glass, the weight of the liquid on top serves to slightly increase the density of the liquid below it. the bubble then accelerates towards it's own density, which is less than any of the liquid at all, since it's a gas. when you move the glass to the left(or right), the pressure shifts slightly from downward to the side, therefor the bubbles would naturally be accelerating away from the denser liquid.

am i correct?
 

SpartaBard

Well-Known Member
Team MTBNJ Halter's
yeah, the liquid pretty much wants to stay in place as per the Law of Inertia.
 
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DANSPANK

Guest
Post-ride this afternoon, I shall partake in a hop/barley/water combo whilst enjoying my achey muscles, perhaps a margarita and the cinco de mayo festivities whilst waiting for my amazingly fortunate girlfriend to arrive at a public house establishment. A liquid-density, bubble-travel study shall then ensue.

I still remain with my original hypothesis that the bubbles are simply traveling vertically but, when compared to the acceleration of the glass horizontally, appear to have a diagonal trajectory.
 

anrothar

entirely thrilled
it's similar, but not the same to leaning in a turn. if riding in a straight line, you need to keep a vertival line, but when turning, keeping that vertical line would have you falling over because of the g-forces, which are what shift the slightly denser liquid to the side of the glass while it is in motion.

remember, don't tilt the glass, just move it horizontally. could slide it across the bar in front of you if you like. viva mexico! viva la revolucion!
 
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DANSPANK

Guest
So my frothy brew really didn't have much gas in it but the few bubbles I did see seemed to just be rising vertically and just the sliding motion of the glass across the table gave the impression that the bubble was travelling diagonally. Sorry sir, but I'm not convinced. I intend to study this more thoroughly...
 

anrothar

entirely thrilled
yeah, but it's diagonal in the oppossite direction than what would be caused by moving the glass horizontally. if the bubble just floated straight up, regardless, when sliding it to the right, it would appear the bubble was rising diagonally to the left. but it wont. it will appear the bubble is rising diagonally to the right.

carlsberg in a proper glass would be an excellent beer to try it with.
 
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DANSPANK

Guest
Ahhh, there's the reason for the anomaly - I used Stella.
 
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