Naked Science Forum

General Science => General Science => Topic started by: neilep on 08/09/2008 20:08:36

Title: Why Does A Shaken Fizzy Drink Can Roll Slower ?
Post by: neilep on 08/09/2008 20:08:36

Dear Peeps Who Sing This !

"Roll me over lay me down and do it again
Roll me over in the clover, roll me over lay me down and do it again"


As a sheepy, I of course indulge in consuming fizzy drinks !


See my fizzy can of pop ?

 [ Invalid Attachment ]

Hmmm...what delicious treat resides inside I wonder ?

Now then, If I take another one....shake it hard and then place both of them at the top of a slight incline...the shaken one will roll down slower !!


Why's that then ? Why does the non shaken one roll faster ?

I don't know.. I simply do not have a freaking clue !!

Oh how I wish I knew !...will someone who knows this tell me ?

Thanks

Hugs and shmishes


Neil
Soda Pop Problem Asker

xxxxxxxxxxxxxxxxxxxxxxxxxxxx

mwah mwah mwah mwah !!!

Title: Why Does A Shaken Fizzy Drink Can Roll Slower ?
Post by: RD on 08/09/2008 21:44:58

You have increased the moment of inertia of the shaken can.
I think the liquid in the shaken can will be slightly more dense because some of the dissolved gas has escaped from the drink,
(although the gas is still in the can and the masses of the contents of the two cans are the same).

The more dense liquid will have a slightly higher moment of inertia, so that can will be slower to roll.

Title: Why Does A Shaken Fizzy Drink Can Roll Slower ?
Post by: Bored chemist on 09/09/2008 19:45:29

Nice try, but the gas and liquid in a sealed tin are at equilibrium. Shaking it can't affect that so there must be another explanation.
Incidentally, has anyone got a couple of tins of pop and a video camera?

Title: Why Does A Shaken Fizzy Drink Can Roll Slower ?
Post by: RD on 09/09/2008 20:32:54

This source says it's increased pressure increasing the frictional force between the liquid and the can ...
http://homepage.mac.com/cbakken/physlab/plab97/labs/hfakhruddin/popcan.html

If dissolved gas has escaped from the liquid to cause the increased pressure,
 the liquid must be more dense (and more viscous) as a result.

Re: equilibrium...
    if you compare opening a recently shaken can with a rested can you will discover that their contents are not in the same state,
    (don't send me your dry-cleaning bill if you do try this  [:)] )

Title: Why Does A Shaken Fizzy Drink Can Roll Slower ?
Post by: Bored chemist on 09/09/2008 20:43:44

We have all done that experiment, but the system is at eqm in the sealed tin, and it remains that way until the tin is opened.
Have you done the experiment where you shake the tin, then let it settle, then open it. How would the CO2 know to go back into solution? From a molecular point of view the speed of shaking is very slow.

Title: Why Does A Shaken Fizzy Drink Can Roll Slower ?
Post by: RD on 09/09/2008 21:42:55

On second thoughts, increasing density cannot be the explanation for increased angular momentum when the can is rotating vertically... 

 [ Invalid Attachment ]

http://homepage.mac.com/cbakken/physlab/plab97/labs/hfakhruddin/popcan.html


e.g. if this vertical can was half-full of a liquid which was twice as dense, its moment of inertia would remain the same.


So it must be increasing friction/viscosity which slows the shaken can.

Title: Why Does A Shaken Fizzy Drink Can Roll Slower ?
Post by: that mad man on 10/09/2008 17:53:55

Any bubbles newly created even under pressure will always want to rise.
If the can is rolling then the bubbles created will rise and at the same time slow the momentum of the liquid causing it to lag behind.

Possibly..maybe..