Brain Teasers Optical Illusions Puzzle Hunts Codes & Ciphers Mechanical Puzzles
Personal Links
Browse Teasers
Search Teasers

Block of Ice

Science brain teasers require understanding of the physical or biological world and the laws that govern it.


Puzzle ID:#26973
Fun:*** (2.82)
Difficulty:*** (2.17)
Submitted By:phrebh*us****
Corrected By:phrebh




Warbucks and Swig were arguing about the best way to melt ice when Fred walked up.

Warbucks was saying, "That's ridiculous, the best way to melt a block of ice is to put it in the oven."

To which Swig replied, "Nonsense, boiling water is the way to go. You drop the block into a pot of boiling water and it will melt much quicker than in the oven."

"Listen," Warbucks averred, "even an oven set to only 200 degrees Fahrenheit, the block would melt faster than in your boiling water."

Seeing that Fred had approached, and knowing Fred's penchant for all things esoteric, Swig asked him to intervene. Swig told Fred that he thought that the fastest way to melt a block of ice, without breaking it up first, would be to drop it in boiling water. He also told Fred that Warbucks insisted that a warm oven would be the fastest method. He then asked Fred which of them was right.

Fred simply replied, "why, neither of you, of course."

What is the fastest way to melt a block of ice without first breaking it up into smaller pieces?

What Next?


See another brain teaser just like this one...

Or, just get a random brain teaser

If you become a registered user you can vote on this brain teaser, keep track of
which ones you have seen, and even make your own.



Nov 17, 2005

NEAT! I love trying to figure out the answer and getting to learn a little science along the way. Makes me want to try it out.
Nov 17, 2005

Yay! A good science teaser!
Nov 17, 2005

phrebh, there is no scientific basis for your conclusion that running cool water over ice will melt it more quickly than hot water. This would suggest that global warming would actually SLOW the melting of the polar ice caps instead of speeding up the process.

Although placing an ice cube in the oven may be pure conduction in air, putting an ice cube in boiling water uses both conduction AND convection. Since the hottest water at the bottom of the pot is constantly rising to the top, there is a huge amount of natural convection taking place. Try this experiment at home. I can assure you that placing an ice cube in boiling water will melt it faster than running it under cool water.

Finally, there are a few ways (though not safe) to melt an ice cube even faster. For example, increasing the pressure very quickly (with an explosion, for example) would cause ice cube to vaporize in fractions of a second.
Nov 17, 2005

Make a bunch of blocks and try it. You'll see that I'm correct.
Nov 17, 2005

Heyllow phrebh, I liked your teaser. I checked it out, the water IS fastest. I knew this, in second grade we did a lab on how to melt ice fastest with any way we wanted. When someone finally went to the sink, t melted within seconds. good job!
Nov 18, 2005

All ovens, boiling, and explosions aside, running hot water will melt ice faster than running cool water in the same conditions. This is a fact. The hotter the water, the faster the ice will melt, period. Prove me wrong.
Nov 18, 2005

The results in this teaser have been proven by experiment: heat transfer is rarely intuitive. And, since I am the one to make the initial assertion, it is up to you to prove me wrong.
Nov 18, 2005

i liked it and i figure if its wrong oh well its just for fun anyways. good one
Nov 19, 2005

Nicely done - and i believe phrebh is right. This is also the case with frozen foods. Good job!
Nov 19, 2005

Phrebh, You're right, it is up to me to prove you wrong since you posted the original question. So I did just that. I set up experiments to your specifications as follows.

Experiment 1: Melt ice with cool running water.
Experiment 2: Melt ice with hot (180 deg F) running water
Experiment 3: Melt ice with standing boiling water.

Experiment Results:

1 (cool running water): 18 seconds to melt
2 (hot running water): 7 seconds to melt
3 (standing boiling water): 7 seconds to melt

As you can see from experiments 1 and 2, where water temp was the only variable, hot water melts ice faster. Experiment three shows that standing boiling water will melt ice as fast as running hot tap water (less convection, but more conduction).

Phrebh, you are absolutely right that convection will melt ice faster than conduction alone (given equal temperature water), but there is NO truth to the idea that cool water will melt ice faster because the temperatures are closer together. I would be interested in knowing where you got this strange information from.

I encourage anyone reading this to try this at home (it only takes a few minutes) and report your results.
Nov 19, 2005

I actually saw it on a television show, Good Eats.

I think the problem is different initial conditions. You'll notice that in the teaser I say to use blocks of ice, not ice cubes. Mass matters in thermodynamics and water is very a very strange compound, especially when it comes to state changes. Try using margarine tubs to create the ice blocks.
Nov 20, 2005

phrebh, I assure you that you are wrong about cold water melting ice faster. One of the basic laws in nature is that rate of heat transfer is proportional to the difference in temperature, thus the larger the temperature difference, the great the rate of heat transfer to the ice. Newton said this hundreds of years ago and nobody since then has proven him wrong. I really doubt that you'll be the first. Thus, even though running cold water water melts ice faster than a pot of boiling water and an oven, running hot water over the ice will melt it faster than running cold water.
Nov 22, 2005

"The oven is even worse because of the complete absence of external convection. All the block is doing is keeping your oven cool, which actually makes it the slowest way to melt a block ice short of leaving it in the freezer."

The fastest of the 2 would be boiling water even by your own teaser. Therefore Swig is correct.
Nov 22, 2005

GOOD EATS, HUH!! He's telling us how to thaw food to minumize breeding those fun little critter that will cause us to spend a long night in a mans favorite place to read. If you want to use hot water iI recommend an investment in some PEPTO!!
Nov 28, 2005

Well, I'm glad there are some other folks in here that have thought this one through.
(user deleted)
Nov 29, 2005

how about you eat the block of ice?
Nov 30, 2005

phrebh, great teaser, loved it and aren't experiments fun?
Dec 02, 2005

I liked your teaser, phrebb, but I must concur with the hot water proponents. The ammount of heat transferred is not always reflected by the change in temperature. While the ice is changing phase to water, it remains at 32 degrees (at least the part immediately undergoing the change) while absorbing the latent heat of liquification. the rate of heat transfer is largely dependent upon the difference in temperatures, although you make a good observation in reference to relative motion between the two substances producing greater convective heat transfer. Still fluids develop a laminar (sp?) layer which tends to insulate and reduce transfer rates.
Dec 05, 2005

How come so many of these science teasers are just plain wrong?
Why don't people do a little homework before posting?
I do have to admit that the bad teaser made me learn more.
Dec 06, 2005

OK, here is my $0.02 worth. There are many ways faster to melt a block of ice then what has been discussed here so far. i.e. explosions, chemical reactions, super high tempertures, etc. But lets assume we are going to limit ourselves to what we have available in the average kitchen. I would then tell you that the fastest way to melt a solid block of ice would be in a microwave oven. Even a convential home type microwave will melt the ice much faster than any of the methods (again assuming readily available in your kitchen) discussed here so far.
Dec 10, 2005

All I know is that too keep the water troughs from freezing keep the water running so I took a guess! Great Debate!!
Dec 12, 2005

You have neither the grasp of physics nor mathmatics to understand how your solution simply cannot be correct.
Dec 12, 2005

I appoligize for my rudeness, study Einsteins Law of heating and cooling or some basic thermodynamics (yes there is such a thing)
Dec 12, 2005

Maybe I should ask for a refund on my BS in Physics.
Dec 13, 2005

it still souned cool! yet won't work at all.
(user deleted)
Dec 13, 2005

The GOOD EATS show talked about was exactly as this problem is described. Four blocks of ice were used - one in the oven, one in boiling water, one in runnng cool water and one I forget where. The block in running water was completly melted while all the other blocks remained. The one in the oven was melted the least. So, I'll take the physical experiment results over anyone's theoretical reasoning.
Dec 13, 2005

I don't think anybody has a problem with the running water melting the ice the fastest (convection is the best means to transport heat.) It's the statement that running cold water vs. running hot water over the ice is what the dispute is about. I can guarantee that running hot water over ice will melt it a lot quicker than running cold water over it (Newton's Law of Convection: Q=hA(Ts-Tf), therefore the rate of heat transfer (Q) is proportional to the area (A) of heat transfer and the difference in temperature between the surface (Ts) and the fluid (Tf).)
Jan 02, 2006

I was thinking of throwing it in a fire but all that would probably do is put the fire out.
Jan 11, 2006

hey, PatH i think you should turn down your temp. gauge 180 will melt your skin off in less than 45 sec.
Jan 12, 2006

You're right. Honestly I have no idea how hot my running water is and didn't have a thermometer that could measure it...bad estimate. I do wish to keep my skin, so I'll keep that in mind.

The point, however, remains the same.
Jan 12, 2006

Wow... you guys should really shy away from thermodynamics. The heat difference between the hot water and ice is greater therefore the transfer of heat occurs at a faster rate, not slower.

And although vaporizing the icecube would be fun, it would result in sublimation, effectively disqualifying for "melting."

Of course, the boiling water has a higher temperature (at sea level) than the oven set to 200 degrees, so it was obviously the lesser choice.

The fastest way to melt the ice, conventionally speaking, would be to flow running hot water over it.
Apr 07, 2006

You really should ask for that refund! Care to cite some credible references that demonstrate any scientific basis for your assertions?
Aug 22, 2006

It sure isn't Mr. Roger's neighborhood. And reason I need to melt ice blocks in a hurry is?

But it was a most interesting teaser and debate.
Nov 03, 2006

i ALWAYS do that. i just put ice in the sink, run cold water over it and BOOM! its melted.
Nov 03, 2006

sorry. i didnt mean for my comment 2 b so mean.
Nov 17, 2006

Everyone seems to have missed the fact that calories melt ice. Faster moving water will melt ice faster than slow moving water, because it moves more water and, thusly, makes more calories available. The oven is less than efficient because the calories are trying to turn the water clinging to surface of block into steam. The surface area increases by squared values while the volume increases by cubed values, so an ice cube has proportionately more surface than an ice block for calorie transfer. If you double the volume of boiling water, you can increase (but not double) the volume of a cube of ice which will melt in a set amount of time. It would take a giant's cauldron to prove a block of ice couldn't be melted quickly.
What about lava as a heat source?
But seriously, no one has considered steam. Steam from my kettle does melt ice quickly.
Nov 19, 2006

And something might be done with alcohol or rock salt.
Nov 29, 2006

Steam will be at higher temperature, but with much less density. The heat transfer coeficient for convection (h) depends on velocity and density of the coolant.
Jan 03, 2007

I'm going to stop the controversy here by submitting a slight correction. Thanks for all of the interest and debate!

Back to Top

Online Now
9 users and 700 guests

Users In Chat
Follow Braingle!
Fold 'N Fly Paper Airplanes
Easy to follow folding instructions and videos.
Copyright © 1999-2017 | FAQ | Widgets | Links | Green | Subscribe | Contact | Privacy | Conditions | Advertise | Braingle Time: 2:24 pm
Sign In Create a free account