melting ice with object in it
 

discussion at work

block of ice, 75 cm high
icesculpted Porsche Carrera, life size, on top of that block

in it, a set of keys for a Porsche Carrera

http://www.q-music.be/static/afb_alg...lok_hoofd1.jpg

the car is outside, on a market square, it's not a cold winter over here, it doesnt' freeze at night at the moment, and we get day temps between 3 and 7 C ( in the shade)

guess the time in secs till the set of keys hits the ground, win the Porsche


that's the basis for the discussion
collegue, is a university bred type
i'm a high school dropout

so he says, easy, just take the weight of the keys, run some formula about the fixed sink rate of an object(mass) in ice, which is not variable and that's it


i'm guessing this sinkrate is A not as invariable, B there are more factors involved, C even if you did calculate it, that result would be of minor importance in the grand scheme of this melting thing

my guess is this sinkrate over the whole time span would be maybe a few inches or something, if it were a block off ice with no external factors, which is not the case, as there are many, many factors( external temp, water used for the ice, how old is the ice, how was the sculpture built, sun light, ice consistency, rain , etc et etc...)

je insists that the weight of the object, as a cause of melting under the object would be linear and predictable enough to come real close to the real result.. and snipped a few times "didn't you learn physics in school?!"

i'm saying, ok , you run the numbers, just make sure you let me have a test drive in it , once you win

any physics guru's who can shed some insight?

I doubt that the pressure exerted by the keys completely embedded in the ice is capable of lowering the melting point to create a downward flow. It takes really high pressures to achieve. The effect is called regelation.

http://en.wikipedia.org/wiki/Regelation

sorry, i am sucky with newton's law of cooling.

but that would chill one bigass glass of scotch!

Why are you not out there with an acetylene torch?

Just sneak out there one night with a propane torch.... ;)

Doh! legion beat me to it.

Torches are lame. Use frikken "laser".
-Chris

Sawzall. 5 Minutes. Do I win?

Better off buying a lotto ticket, the odds are better there.

Okay here's the formula:

Take the weight of the ice and divide it by the temp in F and divide that by the weight of the keys. Then multiply that number by 13.4217 and you have the number of minutes. The exact number of seconds is dependent on global warming in that particular area.

This secret and highly classified formula was extrapolated from a friend under a bridge who did happen to sneak into a Motel 6 one night so it should work.

Good luck and save me a ride.:)

I agree, the keys won't "flow" through the ice.

If it's sunny, and the ice is clear enough for the sun to hit the keys, then the sun will warm the keys which may cause them to melt through the ice faster.

guys, the block of ice is guared :D
they've done this before, last year it was a gold bar


tx steve for that regelation link, from that formula , i can imagine it's going to be pretty tough calculation...

0.0072 °C drop of melting point per additional atm of pressure applied?

i mean, "how much nm of force do keys exert?"
somebody get me a super computer, we need accuracy here this is a mission of great importance!!

Regardless of whatever analyses, computations, and Cray supercomputers you use to try to figure out the answer to win the prize, in the end--just like when picking for the NCAA March Madness basketball tournament--the chick who reluctantly agrees to join the pool just to get everyone to stop badgering her, and picks teams based upon the names of the mascots or colors of the uniforms, will win it all. She won't even be the least interested in cars, by the way.

You could make a smaller more manageable size replica out of ice and do a simulation and figuer it out.

The dimensions might be tricky though. One thing you could do is make a mold of a smaller version of that car - use a MiniChamps model as your positive for your smaller version and time its melt in the same condisitons then just extrapolate for the larger scale.

That is a pretty big block of ice so the weight of the keys might be pretty in significant untill its a few cm from the ground. A simple experiment could provide data for this as well. In fact, if you had a few different blocks of ice cut to varying thicknesses with keys frozen inside you could time their melt rate and come up with the an equation to predict the thaw. The trick though is the fact the your temp fluctuates so unless the temp is constant it does make predictions tricky. You will never know precisely how warm/cold it will be on a given day or night.

Noah may have the best suggestion. Find the hot babe with no brain and ask her for the number or her number...

Wayne, that's what i told him , impossible to calculate with a simple linear formula, he kept saying no, no no, it all doesn't matter, it's just the sink rate
doesn't matter if you take a block of ice 10x10x10 feet, or a narrow cyllinder, 1 feet across , 10 feet high...

that's what pissed me off, i know i'm not a uni grad, but i'm not to stupid to use my imagination, and imagine what factors might affect this whole ordeal,

and once i came up with a number of variables, it seemed pretty clear to me that you just can't calculate this, let alone calculate it with a simple formula.

this regelation thing might even be true, i'm not debating that, i just think it's effect is marginal to say the least, compared to all the other factors

0.0072 C degree decrease in melting point for every ATM increase in pressure?

PAA-LEEEASE what are we talking about here when the subject applying pressure weighs something like, i dunno, 150 grams??

(if anybody has a 997 key with him, and a small scale at hand, for ****'s&giggles)


i agree Noah, it's a guestimation lottery
even if the formula was reasonably accurate to use, it'de still boil down to luck, maybe it would narrow the playing field a bit

but as it stands, there's not enough data, and not enough computing power to actually narrow it with enough accuracy to rely on...


Lube, the dude insists that external temp has no influence on this sink rate inside, argument is , that the external temp never get's to go that deep in the ice, as the ice absorbs it on the outside, now i can agree to some extent with that... but as ice is translucent, the solar energy does penetrate... and that's another one of those things that's near impossible to calculate

then there is ice quality
what water was used? de-mineralized water?
how old was that ice? i know that in sweden they have an ice hotel, they cut the ice blocks in spring, to use em next winter, so the ice settles... is that a factor in this setup? who knows?

this small scale thing is probably the most realistic to calculate the melting of the whole block
but regarding the keys, the smaller scale you go, the more inaccurate you can measure/extrapolate the key behaviour, so that's no good either
and it still doesn't cover the variables of a block of ice on a market place, exposed to the elements...

As a physicist your friend is an idiot. I agree with most all of your points to it being a terrible pain in the A$$ to calculate.

External temp has everything to do with it! The sink rate is meaningless until the keys are a few cms from the ground, until them the ice will provide adequate support.

As for external temps - your friend should live in a Florida orange grove in the winter. They will spray the fruit with water if there is a frost coming and projected temps get below freezing. Why? becuase ice doensn't get colder than 0C and the fruit will tolerate 0C but not lower - the thinn film of ice will actually insulate the fruit from getting any colder.

As kids, we could make igloos and it would actually get rather warm inside them when the outside temps were -10C or -15C.

Those keys are going to sink in porporation to the shinking of the ice which is absolutley dependent on the ambiant temp.

Agree, the small scale will be difficult for key drop determination - that is used more for a rate determination for the shape. A block could most likely be substituted that is in the same general shape I suppose. What would be the tough thing is the ambiant temp fluctuation. Water quality and even the way in which the water was frozen to make the ice. I know that freeze rate and storage temp do play an influance on the ice clearity which would suggest that the formation of the ice chrystals are in fact different at different process conditions. Of course if this was a material like glass, matel some plastics it would have have an influence on the behaviour of the material - water is really a strange substance. Not many things actually expend when they freeze, water will do that.

You got me thinking now. I know that there is enough data on the kinetics of water to model this but the thing that does make it so friggin random is the ambiant temp flucuation and also the fact thatthey want it in seconds! You would have to know the exact temp of the freezer where the block was kept, if it was sculpted in the freezer, what the temps were on route to the park and then what the temps were going to be in order to calculate the thaw rate.

Its doable but there are a bunch of dependent variables that have to understood prior. I would think that a physical chemistry class has done this sort of work. If not, it would be an interesting class exercise on thermodynamics.

Cool...

Another factor is how much sun is going to hit the object. Reflected off the ground/pavement it sits on. It will melt faster at the base and if the sun gets
to beam down on those keys/key fob (darker than the ice?) that will hasten their drop near the end game.

IE: Build a snow man, use 'coal' for eyes/buttons/nose, add sunshine - observe.

no way, i think the biggest unknown is the amount of air moving past that block of ice. more air movement=faster melt.

thx guys, i knew i could count on the brain trust

i'll make a nice summary of it, and have him chew on it :D

Ice can get colder than 0C, but I think you are referring to the latent heat of freezing which delays further cooling temporarily and provides additional buffer to the insulating properties of the ice.

i like the laser idea. get one that isn't in the visible spectrum and heat those keys right up!

if anybody wants to see the progress of the melt

http://www.q-music.be/page/q_ijsblok_fotogalerij

36 hours and still a long way to go

although i expect it to accelerate exponentially as the volume decreases
some variables can be excluded, just noticed they did put a tent over it
so rain probably is out of the loop
although wind and temp still is variable, and i would think that sunlight still has some effect, even if indirectly...




last year they had a different setup, with a gold bar in it worth 25000 euro
that one was 30 ton's worth of ice, and took 34 days to melt


and i suspect the ice block is a lot smaller in volume now

30 ton of ice, or 30 ton of water
that's 500x200x300 cm square, or rather a bit more because of ice expansion

a 997 is
L442 cm x W 180cm x H130 cm
from the pictures the base seems to follow the width and length of the car
that makes it around
L450 cm x W 180 cm xH 75CM

squared off it's smaller then last years block
and then you still haven't taken care off the sculpted form of the car, taken out of the car's ice block...

several factors that would make it melt faster then last year
the temperature now is considerably higher then 01/07
there is less ice
it's not a square cube, more surface

i've gone ahead and voted in for 1159670 seconds... or 13 days 10 hours 7 minutes 0 secs

wish me luck :D

2 days.

http://forums.pelicanparts.com/uploa...1200098627.jpg


i may be optimistic, but this is 408672 seconds/ 6811 minutes / 113 hours, or 4.75 days into the melt

this thing might actually melt in time for my 1159670 prediction... 750998 secs to go.. i'm more worried about it melting too soon then to late

Is the ice magic or are the strawberries magic? ;)

I can assure you, ice gets colder than 0C.

This is totally awesome. How does one go about placing a guess - or is it too late?

how do you supose they suspended the key in the water while it was freezing? If there a fishing line or something like that holding it that will also effect its drop rate

Good question. I would guess freeze a slab of ice, place the keys on that slab and then freeze the rest on top.

I dunno....just a wild a$$ed guess (WAG)

Do you have to guess the exact time or does the person who gets closest win? No way you can calculate this. The keys will not sink. The car will melt. That depends on the weather, which is not predictable. That said, if the closest guess wins, you should spend some time and find out how long a pile of dense snow usually takes to melt in the climate you have right now. I would try to dig up historical data etc. From the top of my head, I would expect it to take on the order of 6 weeks to melt down. ;)

George

sorry PoP, but unless you have a cell phone with a belgian account... you can't play
they use text messaging for all sorts of games here

the Porsche will be payed by the .40 cts text messages sent by everybody who wants to play


George, no way it will take 6 weeks, last year the block was bigger, it was colder, and it was done in 34 days

close to 1 000 000 seconds now

or about 159670 away from my predicted droptime

135 hours
http://forums.pelicanparts.com/uploa...1200685265.jpg

276 hours ( now)
http://forums.pelicanparts.com/uploa...1200685253.jpg

so that's another 44 hours to go before my prediction is a bust

i've gone and seen it in person
it's realying going fast now, you can see where they joined multiple blocks of ice to make up the block from which they carved the 911 shape
and where those blocks meet, it's going superfast

btw, that's one parameter nobody thought of,
but it seems that 2 blocks 1 cubik meter, joined to form 1 block of 2 cubik meter,
will melt faster then 1 solid block of 2 cubik meter would

i also get the idea that the bottom block is melting faster then the top 911 shape does, i presume that it does so , because of all the melting water that comes down from the top.. .or maybe there's something to do with the ground temp vs air temp... who knows

anyway, in person, it looks a lot smaller then the webcam would make you believe, it's maybe 80cm wide now, not much more

fingers crossed everybody, i could do with a free, brand new 997, because frankly, i don't make nearly enough money to every be able to buy one by the time i saved up the cash, they won't make em anymore ! :D


how sweet it would be, to have that key, drop out of the block from the side, at something like 1159670 seconds...
just a little sound, of plastic and metal on stone... *plink*

Bunch of years back a NYC radio station was giving away a 944 every week.

They'd play a song montage and if you were caller 10 and had the songs/artist correct you were in the running for the week.

Every weekend the entrants would go to a Mall and pick a key out of a fishbowl, the key that started it got you the car.

I got into the running but could not claim it as I did not have a valid license, long story. So I made a deal with my boss, he claims it and we split it. He was driving a DeLorean and wanted a 308. He would sell the 944 for the down on the 308 and i kept the Delorean.

Anyway we get there and wait our turn to pick the key. I pull one out of the bowl and take one look at it. It was a blank with a couple of quick notches filed into it, obvious it would not start even a lawn mower.

Someone in the line before us picked the correct key so we were spared the pain of attempting to start it.

A bunch of us "contestants" hit the bar and had a good time consoling each other and getting downright pissed.

The girl who won it came in and everyone threw money on the bar to buy her some drinks.

Turns out she had been unemployed for a bit, had racked up some bills, needed a few thousand dollars in dental work done urgently and had just landed a job the day before but had no car and no reasonable way to get to work.

On the hopes that she would win she had made a deal with a local car dealership to take the car at a reduced value. In return she got a brand new car, basic no frills transportation, and enough cash to get her out of debt and also pay for her dental work.

The rest of us "losers" unanimously agreed that the right person won that day.

34 days are 5 weeks, by the way, so I am pretty close with my coarse guess from 3000 miles away.

You didn't mention it was in a tent.

George

you're pretty close on last years iceblock which was bigger, and at a colder temperature...


i guess the tent is to slow it down, rain can't touch it, no direct sunlight

How many hot chicks standing around the slab of ice?
Take that number and
multiple it by the number of healthy men in the area
divide by the number of men standing next to their wives
which is later multiplide by the number of number of men who are married and haven't gotten any
this total is now divided by the cost of the car.

Or take the easy way out and ask a cute girl when her birthday is and what time she was born.
so month + date = number of days from start and the birth time should put you in nanoseconds ...

Geez, simple elementary math will go a long way these days :)


interpolaratic expotentional lazer baiting pediazombic numbers reduced from the calculations used in basic quatum physics gets so hairy at times. Plus they are cheating by using a tent. So, go put the Clay back in the corner of that huge 30,000ft computer lab room. They have already figured some astro-physists would have already calculated it out spoiling all the fun for the non-geeks!

it's at 1132366 secs
7.5 hours left on my prediction

it's like 12-13 degrees C out there, weather man mentioned an all time high record for this time of year...

that block is getting pretty thin now, i'm kind hoping that the bottom block will get to weak to support the top part, and the top one will fall/slide off and shatter

not implausible if you look at it
http://forums.pelicanparts.com/uploa...1200821815.jpg

http://forums.pelicanparts.com/uploa...1200958521.jpg


so i went bust on my first prediction
made a second one, and it looks like a close call
the key was visible this afternoon, just a mm or 2 from the surface
radio announced that it's on top now, loose

crowd is building, officials are there, can happen any minute now
it's 00h36, my time was 1h16 ish

damn this is exiting stuff

my nephew is a student not far from there, told him to start drinking coffee so he can make a last ditch effort an start pissing on it at 1h16, 5 secs

C'mon Stijn!

i'm defrosting my freezer just to like get a feel for things