mel jacobson on fri 16 jul 04
several important things that have not been covered:
cut a hole in your teapot. six times larger than the exit hole
of your spout. tiny holes plug/and few use loose tea.
so, the big hole works the best. it is a funnel...that is how
it works. big entrance, small exit. makes for a nice pour.
rich/full flow of tea into the cup.
keep your spout tapered. do not do funny outward tapers etc.
just makes the tea spread in funny patterns as you pour it.
a sharp/razor sharp lower edge of the spout will cut the
flow of tea..no drips.
a nice hole in the cover. let air in. just like a gas can.
it is a simple physics problem. air in forces the liquid
out in a flow. think of a fire hose. lots of pressure/small
opening. and, why would tea spin, splash, google, drip?
the opening for the tea to come out is not shaped
in a perfect funnel taper.
makes sense.
my god, i did science. what a concept.
mel
From:
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web site: my.pclink.com/~melpots
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John Rodgers on sat 17 jul 04
Ivor,
You are quite right. The flat lid against the rim of the glass after
filling to capacity is the condition. Once inverted, atmospheric
pressure will hold sway over gravity.The other method is to submerge the
glass in water, invert it and then raise the glass to the surface but
not so much so that the rim breaks the water surface. Here again,
atmospheric pressure will hold sway against gravity.
Good high school physics parlor tricks to demonstrate the effects of
atmospheric pressure, and lead into discussions of what is and what is
not, a vacuum. That is to explore the question "Is water drawn down the
pipe by a vacuum or gravity, or is it pushed by atmospheric pressure??"
Good question.
Regards,
John Rodgers
Chelsea, AL
Ivor and Olive Lewis wrote:
>Dear John,
>I would like to see you do that trick without placing a lid on the rim
>of the glass once it has been filled to capacity and inverted. It is
>theoretically possible according to the conditions and the maths. But
>to be certain the orifice has to have a seal against which air
>pressure can act. Or am I not thinking this one through properly.
>But your argument relating to the egress of Tea is sound.
>Best regards,
>Ivor
>
>
>>I can turn a completely full glass of water upside down and not a
>>
>>
>drop
>
>
>>will fall out regardless of Gravity's effort. Put a vent in the
>>
>>
>glass
>
>
>>for the air pressure to do it's part and every drop will drain. Of
>>course certain conditions must be met to demonstrate this.
>>
>>
>.
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
>
>
Ivor and Olive Lewis on sat 17 jul 04
Dear Mel,
<<.... air in forces the liquid out in a flow....>
Sorry friend, Gravity pulls tea out of the spout.
Think about it ! Think "Waterfall"
But I agree with everything else except the strainer hole. Fair enough
for the tea bag users. I like to have the total area of the strainer
holes at least twice the area of the diameter of the exit for a tea
leaf style pot.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
John Rodgers on sat 17 jul 04
Ivor, there should be a caveat given........ gravity does some of the
work, air pressure does some of the work. Together they get it done ....
tea in the teacup!!
I can turn a completely full glass of water upside down and not a drop
will fall out regardless of Gravity's effort. Put a vent in the glass
for the air pressure to do it's part and every drop will drain. Of
course certain conditions must be met to demonstrate this.
Best regards,
John Rodgers
Chelsea, AL USA
Ivor and Olive Lewis wrote:
>Dear Mel,
><<.... air in forces the liquid out in a flow....>
>Sorry friend, Gravity pulls tea out of the spout.
>Think about it ! Think "Waterfall"
>But I agree with everything else except the strainer hole. Fair enough
>for the tea bag users. I like to have the total area of the strainer
>holes at least twice the area of the diameter of the exit for a tea
>leaf style pot.
>Best regards,
>Ivor Lewis.
>Redhill,
>S. Australia.
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
>
>
>
wayneinkeywest on sun 18 jul 04
Ivor:
That's an easy trick, often demonstrated. Simply put a sheet of
moistened paper across the top of the glass, making contact with the
liquid, then flip the glass. Voila.
Since there is no opening for air to enter that now "closed" system
(the glass with water), there is nothing to displace the water, and
it remains in the glass. Try it.
Wayne Seidl
Key West, Florida, USA
North America, Terra
Latitude 81.45W, Longitude 24.33N
Elevation 3.1 feet (1m)
----- Original Message -----
From: "Ivor and Olive Lewis"
To:
Sent: Saturday, July 17, 2004 9:59 PM
Subject: Re: spout primer
> Dear John,
> I would like to see you do that trick without placing a lid on the
rim
> of the glass once it has been filled to capacity and inverted. It
is
> theoretically possible according to the conditions and the maths.
But
> to be certain the orifice has to have a seal against which air
> pressure can act. Or am I not thinking this one through properly.
> But your argument relating to the egress of Tea is sound.
> Best regards,
> Ivor
> > I can turn a completely full glass of water upside down and not
a
> drop
> > will fall out regardless of Gravity's effort. Put a vent in the
> glass
> > for the air pressure to do it's part and every drop will drain.
Of
> > course certain conditions must be met to demonstrate this.
> .
>
>
____________________________________________________________________
__________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your
subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
Ivor and Olive Lewis on sun 18 jul 04
Dear John,
I would like to see you do that trick without placing a lid on the rim
of the glass once it has been filled to capacity and inverted. It is
theoretically possible according to the conditions and the maths. But
to be certain the orifice has to have a seal against which air
pressure can act. Or am I not thinking this one through properly.
But your argument relating to the egress of Tea is sound.
Best regards,
Ivor
> I can turn a completely full glass of water upside down and not a
drop
> will fall out regardless of Gravity's effort. Put a vent in the
glass
> for the air pressure to do it's part and every drop will drain. Of
> course certain conditions must be met to demonstrate this.
.
Earl Krueger on mon 19 jul 04
On Jul 17, 2004, at 7:33 AM, John Rodgers wrote:
> Ivor, there should be a caveat given........ gravity does some of the
> work, air pressure does some of the work. Together they get it done
> ....
> tea in the teacup!!
Ivor,
How did you let this one slip past you ???
Doesn't gravity, in fact, do all of the work !
John,
Gravity is a primary force. Air pressure is
a secondary force produced by the effect
of gravity on air. So in fact all of your forces
involved in pouring tea are a result of gravity.
(Hmmm??? Wonder if electrostatics comes
into play at all?)
John, Wayne,
I can turn a completely full glass of water upside
down and not a drop will fall out
regardless of Gravity's effort. Put a vent in the
glass < or a drop of detergent > and every drop
will drain. Of course certain conditions must be
met to demonstrate this. (Caveat below.)
Ain't science grand fun....
Earl K...
Bothell, WA, USA
Caveat: The opening of the glass must be
very small. Surface tension of the water will
prevent air from entering. Detergent will reduce
the surface tension allowing air to enter and the
water to drain.
wayneinkeywest on mon 19 jul 04
Earl! that's "cheatin'" !
If you are relying on your caveat that the opening has to have a
severely reduced size, then you are not involving gravity to begin
with. What would be involved in holding the water into that glass
would involve the molecular attraction principle that bonds water
(similar) molecules together. Gravity is the force opposing
molecular attraction (and the resultant vacuum in a closed container
situation), once the glass is inverted. With a small enough
opening, cohesion of water combined with vacuum cannot be overcome
by the "weaker" force of gravity acting on just those molecules at
the opening, and the water stays where it is. I suspect that vacuum
is the stronger of the forces involved here.
Wayne Seidl
Key West, Florida, USA
North America, Terra
Latitude 81.45W, Longitude 24.33N
Elevation 3.1 feet (1m)
"Nature may abhor a vacuum, but I make a living with mine!"
----- Original Message -----
From: "Earl Krueger"
To:
Sent: Monday, July 19, 2004 5:05 AM
Subject: Re: spout primer
> On Jul 17, 2004, at 7:33 AM, John Rodgers wrote:
> > Ivor, there should be a caveat given........ gravity does some
of the
> > work, air pressure does some of the work. Together they get it
done
> > ....
> > tea in the teacup!!
>
> Ivor,
> How did you let this one slip past you ???
> Doesn't gravity, in fact, do all of the work !
>
> John,
> Gravity is a primary force. Air pressure is
> a secondary force produced by the effect
> of gravity on air. So in fact all of your forces
> involved in pouring tea are a result of gravity.
>
> (Hmmm??? Wonder if electrostatics comes
> into play at all?)
>
> John, Wayne,
> I can turn a completely full glass of water upside
> down and not a drop will fall out
> regardless of Gravity's effort. Put a vent in the
> glass < or a drop of detergent > and every drop
> will drain. Of course certain conditions must be
> met to demonstrate this. (Caveat below.)
>
> Ain't science grand fun....
>
> Earl K...
> Bothell, WA, USA
Ivor and Olive Lewis on mon 19 jul 04
Dear Wayne,
This was one of those amusing tricks done for us when we were kids at
birthday parties.
It would recur as a topic when we were taking junior physics. Half a
pound of water in a tumbler is no match for air pressure of fifteen
pounds per square inch.
Thinking again about the teapot. When the outlet from the spout is
level with the level of tea in the pot there is no pressure
differential. It is possible to calculate the atmospheric differential
a tea is poured knowing that the column of water of an atmospheric
barometer is about 10 metres.
I think gravity rules anyway.
Best regards,
Ivor
Ivor and Olive Lewis on tue 20 jul 04
Dear Earl,
You ask <<(Hmmm??? Wonder if electrostatics comes into play at all?)>>
It has to. Otherwise fluid tea would not wet the glaze, nor would
capillarity come into play, pulling fluid round the rim of the spout.
Which is why Mel tells us to make the rim have a sharp edge to
interrupt the flow.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
.
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