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Old October 11th 07, 04:57 AM posted to rec.aviation.piloting
Le Chaud Lapin
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Posts: 291
Default Backwash Causes Lift?

On Oct 10, 8:38 pm, Jeff Lawrence wrote:
In article .com,
says...
It is not a matter of whether I like it or not. It is something that
simply does not happen. There is no sucking force.


My vacuum cleaner begs to differ. Yes, there is a "sucking force," it's
called "suction".

My vacuum cleaner (with the proper wand attachment) can generate enough
of this sucking force--which you say does not exist--to lift an 8 lbs.
bowling ball up against the force of gravity. If there is no "sucking
force" then what keeps the bowling ball up?


You're joking the sucking force right?

The bowling ball is being kept up it because...

1. Itstarts with 14.7 lbs/inch^2 of pressure all around it.
2. Your vaccum, when placed on the bowling ball, rarefies the air in
the wand
3. There is no longer enough air to push on the bowling ball.
4. If the area that is covered by the ball is 1 square inch, and the
vacuum is perfect, that would be enough to hold the bowling ball with
vacuum.
5. Though vacuum is not perfect, area is undoubtedly greater than 1
square inch, so it still works out to be enough to lift 8 lbs.

This 14.7 lbs per square inch is the same pressure that causes mercury
to rise in a rarefied tube 29.92 inches at standard atmosphere.

-Le Chaud Lapin-