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Offline Barman

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Physics Question
« on: September 21, 2008, 12:05:59 PM »
This has bothered me for a while... so can any of you knuckleheads brainy bonces out there help me...?

Take a container that can be made air-tight - a 2l pepsi bottle for instance.
Half fill it with cold water, screw on the cap and give it a bloody good shake
Open the top and... nothing happens.  noooo:

Now...

Take the same bottle and half fill with hot water
Give it a bloody good shake (not forgetting to screw the top on tightly first)...
Unscrew the cap and "fizzzzz", pressure has built-up inside the bottle  eeek:

Where does that come from then...?  shrugs:
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Offline Snoopy

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Re: Physics Question
« Reply #1 on: September 21, 2008, 12:18:44 PM »
The hot water cools as it is shaken. This causes it to contract creating a slight vacuum in the bottle. As you unscrew the cap the "Fizz" is air rushing to fill that vacuum.  whistle:


NEXT!
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Offline Barman

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Re: Physics Question
« Reply #2 on: September 21, 2008, 12:35:55 PM »
Quote from: Snoopy on September 21, 2008, 12:18:44 PM
The hot water cools as it is shaken. This causes it to contract creating a slight vacuum in the bottle. As you unscrew the cap the "Fizz" is air rushing to fill that vacuum.  whistle:


NEXT!
Nope!  noooo:

The pressure is positive...
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Offline TG

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Re: Physics Question
« Reply #3 on: September 21, 2008, 01:29:22 PM »
Dunno.

Lets talk about breasts.  ;D
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Offline Barman

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Re: Physics Question
« Reply #4 on: September 21, 2008, 01:29:54 PM »
Quote from: TG on September 21, 2008, 01:29:22 PM
Dunno.

Lets talk about breasts.  ;D
(  o  Y  o  )  cloud9:
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Offline Snoopy

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Re: Physics Question
« Reply #5 on: September 21, 2008, 01:36:34 PM »
Quote from: Barman on September 21, 2008, 12:35:55 PM
Quote from: Snoopy on September 21, 2008, 12:18:44 PM
The hot water cools as it is shaken. This causes it to contract creating a slight vacuum in the bottle. As you unscrew the cap the "Fizz" is air rushing to fill that vacuum.  whistle:


NEXT!
Nope!  noooo:

The pressure is positive...

Sorry but you know I'm right. That is why all hot water systems have an "Expansion" tank. whistle:
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Offline Nick

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Re: Physics Question
« Reply #6 on: September 21, 2008, 01:36:47 PM »
Professor Wenchy has her own thread for this stuff  whistle:
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Offline Snoopy

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Re: Physics Question
« Reply #7 on: September 21, 2008, 01:37:49 PM »
And where is she when she is needed?  angry041:
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Offline Nick

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Re: Physics Question
« Reply #8 on: September 21, 2008, 01:38:15 PM »
IKEA
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Offline Snoopy

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Re: Physics Question
« Reply #9 on: September 21, 2008, 01:41:05 PM »
Prolly  ::)
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Offline Barman

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Re: Physics Question
« Reply #10 on: September 21, 2008, 01:44:50 PM »
Quote from: Snoopy on September 21, 2008, 01:36:34 PM
Quote from: Barman on September 21, 2008, 12:35:55 PM
Quote from: Snoopy on September 21, 2008, 12:18:44 PM
The hot water cools as it is shaken. This causes it to contract creating a slight vacuum in the bottle. As you unscrew the cap the "Fizz" is air rushing to fill that vacuum.  whistle:


NEXT!
Nope!  noooo:

The pressure is positive...

Sorry but you know I'm right. That is why all hot water systems have an "Expansion" tank. whistle:
Yes... cos it expands when you heat it...

Have you tried the bloody experiment or not???   Banghead

John Noakes didn't have these problems on Blue Peter...  noooo:
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Offline Snoopy

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Re: Physics Question
« Reply #11 on: September 21, 2008, 01:48:17 PM »
Did it at school at least 50 years ago. Mind we used a screw top glass bottle 'cos PET bottles hadn't been invented.
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Offline Barman

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Re: Physics Question
« Reply #12 on: September 21, 2008, 01:49:14 PM »
Quote from: Snoopy on September 21, 2008, 01:48:17 PM
Did it at school at least 50 years ago. Mind we used a screw top glass bottle 'cos PET bottles hadn't been invented.
Ah... that's why you've forgotten that the pressure increases then...  point:
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Offline Snoopy

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Re: Physics Question
« Reply #13 on: September 21, 2008, 01:58:15 PM »
 razz:

I failed Physics anyway
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Offline Barman

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Re: Physics Question
« Reply #14 on: September 21, 2008, 02:00:43 PM »
Quote from: Snoopy on September 21, 2008, 01:58:15 PM
razz:

I failed Physics anyway
No wonder then...  noooo:
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