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Re: settle a dispute

Posted: Sat Oct 08, 2011 10:57 am
by r90s
Anyone try to prove it yet?


Because I just did:


Image


And here is what happened:


http://www.youtube.com/watch?v=TQ3rL-2u ... rofilepage

The two lengths of tubing showed a difference in pressure as indicated by the movement of the water in the loop.

Cheers,
Jon-Lars

Re: settle a dispute

Posted: Sat Oct 08, 2011 1:58 pm
by robert
I just did the same test with mercury sticks and the levels were even.

Re: settle a dispute

Posted: Sat Oct 08, 2011 2:12 pm
by dougie
Pressure = force per unit of area which only depends on the internal diameter of the hose.
It does not depend on the volume of the hose, which is also determined by its length.
In this case vacuum is negative pressure, but the same rule applies.

Re: settle a dispute

Posted: Sat Oct 08, 2011 2:58 pm
by r90s
Boyle's law:

P1V1 = P2V2

Re: settle a dispute

Posted: Sat Oct 08, 2011 3:08 pm
by Major Softie
r90s wrote:Anyone try to prove it yet?
Because I just did:
The two lengths of tubing showed a difference in pressure as indicated by the movement of the water in the loop.
Cheers,
Jon-Lars
robert wrote:I just did the same test with mercury sticks and the levels were even.
LOL!!!

This makes the title of this thread even more ironic.

Re: settle a dispute

Posted: Sat Oct 08, 2011 3:10 pm
by Major Softie
Rob Frankham wrote:
Major Softie wrote:You do realize that, if this were true, no vacuum gauge in the universe could work accurately unless designed only for one length of tubing.
If this comment is in reponse top my previous post, then no, I don't realise that... in fact I'd really like to know how you get that from what I said.

Rob
Sorry, Rob, no. It was to r90s. I should have been more clear.

Re: settle a dispute

Posted: Sat Oct 08, 2011 3:23 pm
by robert
The mercury sticks are open to atmosphere. Your closed system is just moving the liquid from one side to the other.

Re: settle a dispute

Posted: Sat Oct 08, 2011 3:55 pm
by r90s
..which shows that the two lengths of hose have different pressures.

Mercury won't show enough movement to be visible to a naked eye - it's too heavy.

I can't do much more here. Study up and give us the math and references to explain your statements. Make a video, post some photos.

I did.

Jon-Lars
Bevrly, WA

Re: settle a dispute

Posted: Sat Oct 08, 2011 4:42 pm
by George Ryals
r90s, when you plumb the long and short tubes together with a tee, they become one tube. One tube, one pressure and one height in both tubes. The only way to have different liquid heights is to have different pressures on top of the liquid in each tube.

Re: settle a dispute

Posted: Sat Oct 08, 2011 4:44 pm
by dougie
Where's StephenB?
We need StephenB here.
Hey Stephen :!: