Read what I said. No heat transfer.
And thus no NET change.
This "lubricating" idea of ice skates, which we all heard in grade school non-science, is suspect, anyway. Look up the more recent theories.
Heh, ouch. Same with steel and real high speed, although, then the metal stays out of the joint afterwards so nevermind...
Tim
-- "I have misplaced my pants." - Homer Simpson | Electronics,
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Bzzt. That's the way I learned it, too. The junior high school teacher even went so far as to say that at -40 degrees, you wouldn't be able to skate because you wouldn't be able to get the phase change. Turns out that THAT is a load of crap. People (crazier than I am) regularly play hockey at temperatures like that.
Check out:
p.
That happened with my very first bandsaw..one of those little Harbor Frieght table top jobbies. I got my Walker Turner shortly after that..and that poor little critter still had that chunk of nylon surrounding the blade 4 yrs later when I gave it to a buddy. No blade welder, no silver solder..he cut the blade and bought a new one.
One of lifes little embaressing moments....sigh
Gunner
No 220-pound thug can threaten the well-being or dignity of a 110-pound woman who has two pounds of iron to even things out. Is that evil? Is that wrong? People who object to weapons aren't abolishing violence, they're begging for the rule of brute force, when the biggest, strongest animals among men were always automatically "right". Guns end that, and social democracy is a hollow farce without an armed populace to make it work. - L. Neil Smith
Yeah, but probably not as embarrasing as being blown out of the water by Ed Huntress for the last few month's, eh?
Jim Kovar Vulcan, Mi
(By the way, I've had two inquiries in the last two weeks, and yes, this is my real name and residence. What's wrong with posting real names here? I guess some people like to hide behind an alias. Now *that* is gutless.)
On Sun, 25 Apr 2004 12:26:16 -0500, Richard J Kinch vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email
I am sorry. I am not completely unaware of latent heat etc, but you obviously know far more than I do.
I misunderstood your post, or misread it. I agree that withouit enormous heat, the hand heat would not affect cutting. I also fell that it will struggle to make any difference, for the same reasons, to the sticking of the icecream to the scoop. There would simply not be enough heat transfer. Apart from which, a hollow aluminium handle would probably do just as well if not better, as long as you held the scoop. Unless you pre-warmed the scoop, all the extra mass of the "antifreeze" would do was to make it harder to get the temp of the scoop up.
If you then tell me that ice skates are not causing the local melting we all learned, then I do not have a hope.
OK. But how is the anti-freeze going to make any difference?
Anti-freeze, as I understand it, is to stop water freezing, not to transfer heat and prevent water freezing. I really don;t see it making any difference here, except perhaps negative _given only hand heat input_.
OK. This is where we part company and you seem to leave me in the past, with my school physucs lessons.
**************************************************** The Met Bureau is LOVE!On Mon, 26 Apr 2004 09:23:18 -0500, Richard J Kinch vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email
But there _is_, or at least there could be, and there _has_ to be energy transfer. Just because it starts as pressure does not mean it stays as pressure. In fact pressure _will_ cause heat.
All theories about whether ice-skates actually melt the ice aside:
But that does not mean that there was no energy transfer or change of state. It means that the energy transferred was rapidly dissipated into the surounding ice.
Your scoop "melted" the icecream in your other post. If you melt ice, you transfer energy. It refreezes just as your icecream did, and for the same reason. As you (I think sort of) said, the surrounding material is colder than the melted area and simply takes the heat away.
**************************************************** The Met Bureau is LOVE!On Mon, 26 Apr 2004 14:27:41 -0400, "Phillip Vogel" vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email
Interesting. But the ambient temp need not define the ice temp. I notice they keep the ice quite warm for skating.
**************************************************** The Met Bureau is LOVE!
It's probably not anti-freeze. It's probably *water* in there.
Water has some interesting properties. It has a really really really large specific heat. Much much much larger than aluminum.
The slug of water is not there to *conduct* heat from your hand to the scoop end of the scooper. It's there to *store* heat. The hot water does a much better job of keeping the scoop warm to melt the ice cream.
How does the water get hot? Ya run the darn thing under hot water before you use it, just like any mom would!!
Jim
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You forgot to mention two things...The whipped in air makes the drink look a lot bigger than it really is. Let a "full" McDonald's shake sit for a couple of hours and note how much the level in the cup drops. And, if you drink it, all that entrained air has to get out of your body somehow, in my case it's usually by the rear exit.
Jeff
Yes, and being born in California and living there until college time, I hadn't experienced freezing weather and all it's pleasures and pains until I came to Taxachusetts, where I stupidly still remain some 50 years later.
It took a slip and fall accident (with an ensuing busted wrist and pelvis) getting out of my car in my own driveway a couple of years ago to make me finaly realize that when stepping onto any icy pavement from a warm building or vehicle that it's wise to pause and wait about twenty seconds for your shoe soles to get cold so they're less likely to melt a slippery layer of water to ruin your day.
I've also noticed that when temperatures get to around minus 10 degrees Farenheit, tire traction on icy surfaces improves greatly, it almost feels like you're driving on bare pavement.
Jeff (Who left his heart in San Francisco...)
Nope..some times I put Ed in the barrel, and some times its my turn. Shrug.
The last time I was embaressed..was when I was caught in de lecto (actually de Rambler ) with the lady on top having a marvelously and totally unihibited and screaming good time, caught by the local sherrif.
Who happened to be her father.
We were both over the legal age by a couple years. Shrug..I felt embaressed for him, as he had watched this nubile and well filled out young lady doing the mindless watusi though heavily fogged windows. I recall well the look on his face with she rolled down the window and said Hi Daddy!
Poor bastard. Sigh. Later when I caught my son doing the same..I knew how he felt, sorta kinda. Daughters of course are different...shrug.
If I was worried about being embaressed, Id never post.
Gunner
No 220-pound thug can threaten the well-being or dignity of a 110-pound woman who has two pounds of iron to even things out. Is that evil? Is that wrong? People who object to weapons aren't abolishing violence, they're begging for the rule of brute force, when the biggest, strongest animals among men were always automatically "right". Guns end that, and social democracy is a hollow farce without an armed populace to make it work. - L. Neil Smith
Indeed. At an office function once, an unfinished carton of ice cream sat around all afternoon. In the end it was 1/2 liquid and 1/2 foam. Really disgusting. I still shy away from that brand, even though I know that they all are that way.
Bob
Without this effect a large portion of Canada would grind to a halt for several months a year. As a kid, playing hockey on the street (this in the days before the widespread use of salt and sand) we would pause our game and move the nets for the odd car or truck that needed 'our' road. Those vehicles had no traction problems (-20) to negotiate the 'rink'. On another note - I scored a pound of sodium metal - long story, perfectly legal - many years ago - and discovered that a piece (maybe a 3/8 inch cube) - when dropped on an ice covered road would burrow its way through the six or so inches of compact ice on said road until it got to the pavement/gravel. Then this little piece of reactive metal would melt a little cavern and sooner or later accumulate enough hot water to 'go critical'. Spectacular is the only way to describe the resulting explosion. Good way to amaze your friends and terrify your enemies. Also a good way to bring in the New Year - Blow up a really large stretch of the local road. Never got caught. Regards. Ken.
Ah, it's nothing that years of therapy can't fix.
Every generation thinks they invented it. Suprise.
Jim
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On 26 Apr 2004 17:31:06 -0700, jim rozen vaguely proposed a theory ......and in reply I say!: remove ns from my header address to reply via email
Seriously. I was getting to all that.
There is a classic illustration of the power of water's SH. You get those "freezer blocks" that you store in the refrig and then use to keep stuff cool in the your cooler. It's coloured water. You could get the same effect with a couple of dribnk bottles full of frozen water...errr..ice. The claims of super space-age materials are good for a laugh!
**************************************************** The Met Bureau is LOVE!On Mon, 26 Apr 2004 21:15:21 -0400, Jeff Wisnia brought forth from the murky depths:
Aha, PROOF positive that Mickey D's shakes (can't call them milk shakes when there's no milk in them) are actually made with solid rocket fuel. What are the implications here? Shall we let the HSD know about it? Headlines tomorrow could be "McDonalds Restaurants Arrested and Quarantined for Terrorism and Sales of WMDs"
Woiks f' me, and the health of millions of Americans would instantly improve.
========================================================== CAUTION: Do not use remaining fingers as pushsticks! ==========================================================
It is important not to confuse heat with temperature.
There were two melting sites postulated, the "cutting" of the bulk product (would require lots of heat because lots of frozen product must be melted), versus the surface of the ball in the scoop (requires negligible heat because the layer need only be very thin to keep it from sticking). I believe the latter occurs but not the former.
The manufacturer claims it is antifreeze. Might be just salt water, or non-toxic glyol.
You don't want the scoop hot, because that yields too much melting too fast. Of course it works, but it will thaw too much of the product served as well as the bulk product. You want just a slight layer of thawing right at the moment of release.
Besides, if you ever have served a crowd, the hand heat is the only make-up supply of heat, but you can serve forever just from that, long after any prior heat is dissipated and the scoop is quite cold (but still above freezing).
In fact, in the normal "steady state" operation with continuous serving, the subcooled, scooped ball sticks to the sub-freezing scoop tip, and one shakes a bit to transfer heat to the scoop tip and release the serving, all from hand heat.
All the folks around here leave the scoops in a small basin with water dribbling into it. That seems to keep them at room temp.
Jim
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