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Author Topic: Why does my wine glass move like this?  (Read 16962 times)

Offline AllenG

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Why does my wine glass move like this?
« Reply #25 on: 14/04/2009 01:24:54 »

Done with a highly calibrated serving fork instead of my fingers.
« Last Edit: 14/04/2009 01:28:09 by AllenG »
 

Offline lightarrow

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Why does my wine glass move like this?
« Reply #26 on: 14/04/2009 08:26:08 »

Done with a highly calibrated serving fork instead of my fingers.
Very good! Did you also try lubricating the fork with a low-viscosity oil?
 

Offline Chemistry4me

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Why does my wine glass move like this?
« Reply #27 on: 14/04/2009 09:16:07 »
That's nice. :)
 

Offline AllenG

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Why does my wine glass move like this?
« Reply #28 on: 14/04/2009 19:10:36 »

Done with a highly calibrated serving fork instead of my fingers.
Very good! Did you also try lubricating the fork with a low-viscosity oil?
Nope.  Non-lubricated fork.

Thanks for all the thoughts folks.
I'm going to stick with the planetary gear hypothesis.
 

Offline yor_on

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Why does my wine glass move like this?
« Reply #29 on: 14/04/2009 23:37:21 »
I was swirling some wine around in a stemmed glass ware and I noticed that if I held the stem loosely between my fingers it would rotate in the opposite direction than I was swirling the wine.
I tried it with and without liquid in the glass and the effect was the same.
Why does it do that?

I made a .gif file to show the effect.

Thanks,

--Allen




I hate to say this but you still haven't showed us the gif with that wine rotating in the opposite direction of the glass? And you haven't done it with the fork either?? Come on, a jug of wine, or two, ah, ok three then, how expensive can it be?

I have this idea that maybe the wine just doesn't rotate at all?
Huh?? Bring me a jug and let's explore :)
 

Offline Chemistry4me

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Why does my wine glass move like this?
« Reply #30 on: 16/04/2009 06:12:29 »
I notice something similar, when I have a cup of water/liquid and I hold it out in front of me then I spin my whole body around, the water/liquid spins in the opposite direction inside the cup.
 

lyner

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Why does my wine glass move like this?
« Reply #31 on: 21/04/2009 13:46:13 »
I think I have sussed out the reason for the whole thing and have explained the reversal in direction when the glass is upside down.
It goes like this.
With the glass the right way up, the centre of mass is above your fingers. Assume that you hold it in the fingers of your right hand.When you push forward, there will be a slight clockwise curvature to the motion initially (your forearm, for instance, will pivot about your elbow).  I think this will continue because you are making a conscious effort at a curved motion. There will be a moment, tilting the glass outwards from the curve, causing more downward force on the table away from the centre of the curve (one section of the base will 'dig in'). The difference in friction forces  (F2 and F3) around the edge of the base will be such as to to produce an anticlockwise force on the base - turning the glass anticlockwise. On the return journey, it is the other side of the base that digs in and the rotation is in the same sense. The diagram was a bit hard to draw but I think it says what I mean.

With the glass upside down, it tilts in the same direction as you are pushing it because the CM is below your fingers. It is the opposite side of the rim which digs in more and so the rotation direction will be in the  opposite sense because F2 would be bigger than F3.

Some actual wine had to be consumed during the investigation. Cheersh!
« Last Edit: 21/04/2009 13:49:56 by sophiecentaur »
 

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Why does my wine glass move like this?
« Reply #31 on: 21/04/2009 13:46:13 »

 

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