From: Andrew McKenna on
Smee R11S wrote:
> Toosmoky wrote:
>> Iain Chalmers wrote:
>>
>>> Perhaps only blimps and air-ships actually "float" in Nev-land since
>>> they manage to keep 100% of their mass out of the water? :-)
>>
>> As ships displace water, so airships displace air...
>>
>
> does that mean spaceships displace space?
:-) Only if you believe that Einstein feller.

--
Cheers

Andrew
From: bikerbetty on

"Andrew McKenna" <NOcmorSPAM3047(a)NObigpond.SPAMnet.au> wrote in message
news:HWxBh.118$8U4.91(a)news-server.bigpond.net.au...
> Smee R11S wrote:
>> Toosmoky wrote:
>>> Iain Chalmers wrote:
>>>
>>>> Perhaps only blimps and air-ships actually "float" in Nev-land since
>>>> they manage to keep 100% of their mass out of the water? :-)
>>>
>>> As ships displace water, so airships displace air...
>>>
>>
>> does that mean spaceships displace space?
> :-) Only if you believe that Einstein feller.
>
my brain hurts

betty


From: Dale Porter on
"Hammo" <hbaj2006(a)aapt.net.au> wrote in message news:C1FCC940.125D7%hbaj2006(a)aapt.net.au...
>
>
>
> On 17/2/07 9:33 AM, in article er5bgd$lb5$1(a)otis.netspace.net.au, "Dale
> Porter" <daleaporter(a)gmail.com> wrote:
>
>> "paulh" <paulh(a)fahncahn.com> wrote in message
>> news:akbbt2dglrucsqm0kug0n0qljgqf3nc2c9(a)4ax.com...
>>> On Fri, 16 Feb 2007 21:45:14 +1100, "Dale Porter"
>>> <daleaporter(a)gmail.com> wrote:
>>>
>>>> "paulh" <paulh(a)fahncahn.com> wrote in message
>>>> news:qi2bt2hq7nbhf2t7lhsl3o12l3fthigvmf(a)4ax.com...
>>>>> On Fri, 16 Feb 2007 18:37:54 +1000, Toosmoky <toosmoky(a)hotmail.com>
>>>>> wrote:
>>>>>
>>>>>> Iain Chalmers wrote:
>>>>>>
>>>>>>> Perhaps only blimps and air-ships actually "float" in Nev-land since
>>>>>>> they manage to keep 100% of their mass out of the water? :-)
>>>>>>
>>>>>> As ships displace water, so airships displace air...
>>>>>
>>>>> Air is compressible, Water isn't. So airships just might push the air
>>>>> aside.
>>>>>
>>>>>
>>>>
>>>> But isn't pushing the air aside also displacing it?
>>>
>>> Not really... theoretically if you displace water then the water that
>>> has been displaced must go somewhere else. That is, the water level in
>>> the bath rises. But in air there would be no increase in 'air level',
>>> but the air would just get denser instead.
>>>
>>> In a real life experiment (with an airship) it would possibly do a bit
>>> of both as the enviroment is far more complex.
>>>
>>>
>>
>> The "level" of air would be irrelevant. To displace something, you are moving
>> it from it's original location. If I came up to you
>> and hip-and-shouldered you out of the way, I would have displaced you. Your
>> level would not have changed (other than your level of
>> annoyance). An airship displaces air by pushing it aside. The air is
>> effectively replaced at that point by an airship.
>
> An interesting point, you also need to consider laminar vs turbulent flow.
> This IS important when considering "levels" of air.
>
> Hammo
>

In the words of Ms Hanson.... "Please explain". What is laminar?

--
Dale Porter
GPX250 -> CBR600 -> VTR1000 + VT250F-J


From: Moike on
Hammo wrote:
> "Moike" <bmwmoike(a)gmail.com> wrote:
>> Hammo wrote:
>>> <bigiain(a)mightymedia.com.au> wrote:
>>>> Hammo <hbaj2006(a)aapt.net.au> wrote:
>>>>> <bigiain(a)mightymedia.com.au> wrote:
>>>>>> Hammo <hbaj2006(a)aapt.net.au> wrote:
>>>>>>> <bigiain(a)mightymedia.com.au> wrote:
>>>>>>>> "Knobdoodle" <knobdoodle(a)hotmail.com> wrote:
>>>>>>>>> "Peter Cremasco" <FirstName.LastName(a)bigpond.com> wrote in message
>>>>>>>>>> <knobdoodle(a)hotmail.com>
>>>>>>>>>>> It also expands when cooled below zero!
>>>>>>>>>>> [cue Twilight-Zone music]
>>>>>>>>>> Below 4 degrees C, I think.
>>>>>>>>>> ---
>>>>>>>>> You're right; but I think it's negative 4.
>>>>>>>> Nope, plus 4, thats why ice floats...
>>>>>>> Eh? Flotation is based on temperature?
>>>>>>>
>>>>>>> That makes no sense.
>>>>>> You are, of course, completely right Hammo, as usual. The expansion of
>>>>>> water as it drops below 4 degrees has absolutely nothing to do with why
>>>>>> ice floats, I must have forgotten to factor in the efficiency of the
>>>>>> cooling system, or the torque on the refrigerator compressor or some
>>>>>> other completely irrelevant detail.
>>>>>>
>>>>>> Lets see:
>>>>>>
>>>>>> http://www.google.com/search?q=why+ice+floats
>>>>>>
>>>>>> Not a single one of the returns there says anything about temperature
>>>>>> having anything to do with why ice floats, does it?
>>>>> So your post and I quote..
>>>>>
>>>>> BigIain: " Nope, plus 4, thats why ice floats..."
>>>>>
>>>>> Tell me what that was supposed to mean.
>>>>>
>>>>> Hammo : I'm, pretty sure that what I posted was "Eh? Flotation is based on
>>>>> temperature? "That makes no sense".
>>>>>
>>>>> I'm looking forward how you managed to interpret that to mean that it is,
>>>>> especially after you pointed out that a temp of "plus 4" was why ice
>>>>> floats.
>>>>>
>>>> I know you're a very busy guy Hamish, but it's all in the context, all
>>>> of which you've quoted up there. Try and follow along:
>>>>
>>>> Clem said "It also expands when cooled below zero!",
>>>> then Peter said "Below 4 degrees C, I think.",
>>>> then Clem said "You're right; but I think it's negative 4.",
>>>> then I said "Nope, plus 4, thats why ice floats..." - pointing out that
>>>> if you had to cool water down below -4 degrees until it started
>>>> expanding, ice _wouldn't_ float.
>>> I don't recall seeing this last bit of your explanation. Has it always been
>>> there?
>>>
>>> I disagree with you. The density of ice does change the colder it gets, and
>>> so even if the change started there, ice would "float". As you know how to
>>> google, look it up, or consult wikipedia for a way to calculate it.
>
>> No, you are wrong. If ice(water) did not begin to reduce its density
>> until -4 C (the assertion Big was rebutting) ice would not float until
>> it was cooled below -4 C. Ice at (say) -2 C would sink.
>
> Hmm, I didn't think that what Big was claiming.

All big was doing was correcting the other poster's incorrect assertion
that the density peaks at -4C.
> It took what he said to
> mean that water increased in density at plus 4 degrees and this is why ice
> "floated".

> you read too much into his simple words. Ice is less dense than
water. Most liquids become more dense when they solidify. I assume you
are aware of this. The effect becomes apparent at 4C.


> Meaning that it was necessary to have a more dense solution to
> enable ice to float.

No he didn't say that.

> To use the analogy of rocks in water (and leaving
> myself wide open) rocks have greater density and so don't float, water less
> dense cf rocks are above them.
>

Not all rocks are less dense than water. The last 8 words of that
"sentence" defy decoding by any of the commonly accepted 'rules' of english.


> As per .. http://www.lsbu.ac.uk/water/phase.html
>
>> The oceans
>> would freeze from the bottom up and life (as we know it) would not exist
>> on this planet.
>
> No they wouldn't. That is just silly.
No it's not. most non-aqueous liquids solidify from the bottom
unless they are exposed to significant top surface cooling.
> The pressure at the bottom of the
> ocean is that same at the surface?
No, I didn't say that. I said that if ice were more dense than water,
as is the case for most liquids that solidify, it would sink to the
bottom, causing the ocians to freeze from the bottom up.

> You don't mention Debuye-Huckle (re
> salinity).
Salinity may vary with depth, but not significantly. If fresh water
were to become more dense when solidifying, salt water would do the
same, (albeit at a different temperature) since the density anomoly of
ice is related to the structure of the water molecule (as you are
presumably aware.)
> As a result, the density will increase as the depth of the ocean
> increases.

No. as you presumably know, water is only very slightly compressible, so
while pressure might increase with depth, the change in density is
insignificant in this context.

> See also glacial theory.
irrelevant.
> Not to mention convection

Convection is what causes cold liquids to sink. If water were to become
more dense as it freezes, this would be part of the reason it would
freeze from the bottom up. (but of course, it doesn't, does it.)


> which would
> be a what, first year high school if not primary school concept?
>
you seem to think that there is a point to be made here.

> See your own comment below.
>> What Big said was perfectly intelligible to anyone who had been
>> listening in year 9 science and who chose to read it in the context of
>> the thread.
>
> Yeah, it is that simple, eh. See your comment above.
Yes, it is relatively simple. I'm glad you agree. So are your
objections the result of your inability to understand simple concepts or
a desire to pretend to sound intelligent. I think I am beginning to
realise why you are no longer involved in scientific research, (if that
is what you did in the lab.)

>> It's sad that someone who lays claim to a scientific background protests
>> about his need to have someone else join the obvious dots for him.
>
> It is Usenet. Who cares?
>

The "it's only usenet" is is generally the last refuge of failed
bullshit artists.

You are the one that cared enough to raise objections.

Pity you only made yourself look silly.


You really are becoming tiresome, Hamish. I expect better quiality bull
from someone like you.

Moike

From: Hammo on



On 17/2/07 9:11 PM, in article er6kd1$v6a$1(a)otis.netspace.net.au, "Dale
Porter" <daleaporter(a)gmail.com> wrote:

> "Hammo" <hbaj2006(a)aapt.net.au> wrote in message
> news:C1FCC940.125D7%hbaj2006(a)aapt.net.au...
>>
>>
>>
>> On 17/2/07 9:33 AM, in article er5bgd$lb5$1(a)otis.netspace.net.au, "Dale
>> Porter" <daleaporter(a)gmail.com> wrote:
>>
>>> "paulh" <paulh(a)fahncahn.com> wrote in message
>>> news:akbbt2dglrucsqm0kug0n0qljgqf3nc2c9(a)4ax.com...
>>>> On Fri, 16 Feb 2007 21:45:14 +1100, "Dale Porter"
>>>> <daleaporter(a)gmail.com> wrote:
>>>>
>>>>> "paulh" <paulh(a)fahncahn.com> wrote in message
>>>>> news:qi2bt2hq7nbhf2t7lhsl3o12l3fthigvmf(a)4ax.com...
>>>>>> On Fri, 16 Feb 2007 18:37:54 +1000, Toosmoky <toosmoky(a)hotmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Iain Chalmers wrote:
>>>>>>>
>>>>>>>> Perhaps only blimps and air-ships actually "float" in Nev-land since
>>>>>>>> they manage to keep 100% of their mass out of the water? :-)
>>>>>>>
>>>>>>> As ships displace water, so airships displace air...
>>>>>>
>>>>>> Air is compressible, Water isn't. So airships just might push the air
>>>>>> aside.
>>>>>>
>>>>>>
>>>>>
>>>>> But isn't pushing the air aside also displacing it?
>>>>
>>>> Not really... theoretically if you displace water then the water that
>>>> has been displaced must go somewhere else. That is, the water level in
>>>> the bath rises. But in air there would be no increase in 'air level',
>>>> but the air would just get denser instead.
>>>>
>>>> In a real life experiment (with an airship) it would possibly do a bit
>>>> of both as the enviroment is far more complex.
>>>>
>>>>
>>>
>>> The "level" of air would be irrelevant. To displace something, you are
>>> moving
>>> it from it's original location. If I came up to you
>>> and hip-and-shouldered you out of the way, I would have displaced you. Your
>>> level would not have changed (other than your level of
>>> annoyance). An airship displaces air by pushing it aside. The air is
>>> effectively replaced at that point by an airship.
>>
>> An interesting point, you also need to consider laminar vs turbulent flow.
>> This IS important when considering "levels" of air.
>>
>> Hammo
>>
>
> In the words of Ms Hanson.... "Please explain". What is laminar?

I looked at Wiki as it has become the "benchmark"
http://en.wikipedia.org/wiki/Laminar_flow

However it has no reference re: airflow. Laminar, smooth, turbulent rough.

This was incredibly important, and has become a consideration of all
industrial/commercial drying, ovens etc that greater efficiency is achieved
with laminar flow.

Hammo