science questions

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Ophir

Golden Member
Mar 29, 2001
1,211
4
81
Originally posted by: KayGee
Originally posted by: dullard
Originally posted by: KayGee
heat transfer in liquids/gases occurs through the process of convection. there will only be conduction within the material that the vessel containing the liquids is made of.
Liquids and gasses both convect AND conduct heat.

not trying to be a smartass, but that's the first time i've heard that. do you have a source? you aren't referring to conjugate heat transfer? i'm just curious.
Umm ... a heat transfer course/book? As long as molecules can collide they can transfer energy by conduction. That's not to say that heat transfer by conduction in fluids is significant, at least when compare to convective heat transfer.
 

dullard

Elite Member
May 21, 2001
25,902
4,487
126
Originally posted by: KayGee
not trying to be a smartass, but that's the first time i've heard that. do you have a source? you aren't referring to conjugate heat transfer? i'm just curious.
Just use knowledge of the world around you.

Imagine a container filled entirely with water. The water and the container are stationary and at equilibrium. The only motion in the water is the random movements of the water molecules. Suddenly you heat the water from the top. What happens?

Is it:
(A) The heat stays at the top of the water forever, so that the bottom stays cold.
(B) The heat conducts to the bottom of the water.
(C) The water starts bulk motion (ie measurable quantities of water move forming currents) moving all around stirring itself, bringing heat to the bottom?
 

Journer

Banned
Jun 30, 2005
4,355
0
0
man...i r dumb ass, lol...i wasn't looking for an exact answer...i just wanted to know if ice cools quicker than hot water heats
 

piasabird

Lifer
Feb 6, 2002
17,168
60
91
This was the question you asked:

"does hot water make water hotter quicker than cold water makes it cold?"

You did not specifically say Ice; You said cold water. That does not really matter much.

A lot depends what you mean by Cold (Ice) 32degrees, what you mean by Hot Water, and what we might consider the average temperature for water or the normal temperature for water.

Here is something to look at. What I am suggesting is tap water is around 70 degrees. So ice is about 32 degrees. It is only about 38 degree difference to get to the point of ice and cold is probably around 40 degrees. So cold would be a 30 degree difference. Hot is kind of a relative term Water boils around 120 degrees, but it really depends on the atmospheric pressure. Tibetan monks at their elevation often drink their tea while it is still bubbling. This is because it boils at a lower temperature. So lets say hot is 95 degrees. It might be as hot as say 102. Think of a Hot Tub as an example.

There is a premise here. If you heat water if you get it past the boiling point it turns into vapor. However, if you get it colder than 32 then it is just colder. It is still solid and it is still ice. For this reason I say it is easier to cool water with ice. You can not put water that is too hot into water, because at a certain point it just turns to water vapor. However, Ice can be colder than 32 degrees, and it does not disappear if it gets colder.

I think if you fill a glass with hot water and you fill a glass with ice water, It will take longer for the glass of ice water to reach room temperature than it will for a glass of hot water say tea to reach room temperature. This is probably because Ice Water has ice in it.
 

Fenixgoon

Lifer
Jun 30, 2003
33,052
12,434
136
Originally posted by: dullard
Originally posted by: KayGee
not trying to be a smartass, but that's the first time i've heard that. do you have a source? you aren't referring to conjugate heat transfer? i'm just curious.
Just use knowledge of the world around you.

Imagine a container filled entirely with water. The water and the container are stationary and at equilibrium. The only motion in the water is the random movements of the water molecules. Suddenly you heat the water from the top. What happens?

Is it:
(A) The heat stays at the top of the water forever, so that the bottom stays cold.
(B) The heat conducts to the bottom of the water.
(C) The water starts bulk motion (ie measurable quantities of water move forming currents) moving all around stirring itself, bringing heat to the bottom?

B&C FTW :D