Why does stirring the ice in a glass of water make the water get cold faster?

[Ave Maria]

Hey everyone. I have done this ever since I can remember. When I get a glass of water or soda or whatever and it is not cold enough I will put ice in it and then stir the ice around with my finger tip. Within a few seconds, the water or whatever I am drinking becomes colder than it was prior to stirring. Why does stirring the ice make the drink colder faster?

 

[Michael]

Hey everyone. I have done this ever since I can remember. When I get a glass of water or soda or whatever and it is not cold enough I will put ice in it and then stir the ice around with my finger tip. Within a few seconds, the water or whatever I am drinking becomes colder than it was prior to stirring. Why does stirring the ice make the drink colder faster?

By stirring the drink, you bring more molecules of water into contact with the ice faster, and in greater numbers than if you did not stir the drink. You're ultimately speeding up the melting of the ice into the drink as well. It's a double win when you stir.

 

[Ave Maria]

By stirring the drink, you bring more molecules of water into contact with the ice faster, and in greater numbers than if you did not stir the drink. You're ultimately speeding up the melting of the ice into the drink as well. It's a double win when you stir.

Oh cool! Thanks for answering my question!

 

[Coelo]

Why does stirring the ice make the drink colder faster?

Heat or cold moves slower though water then it does air. In a perfect world air and water is the same temperature. In our world because the water and air are different that creates a lot of the weather we have.

 

[Lord Emsworth]

Oh cool!

I see what you did there.

 

[CabVet]

Heat or cold moves slower though water then it does air. In a perfect world air and water is the same temperature. In our world because the water and air are different that creates a lot of the weather we have.

You seem to have no idea what you are talking about.

 

[trunks2k]

Heat or cold moves slower though water then it does air. In a perfect world air and water is the same temperature. In our world because the water and air are different that creates a lot of the weather we have.

1.) I don't think you know what you are talking about.
2.) None of that has anything to do with anything the OP asked.

 

[Coelo]

You seem to have no idea what you are talking about.

No you have no idea what I am talking about, nothing new there. Have you ever heard of lake-effect snow?

"Lake-effect snow is produced during cooler atmospheric conditions when cold winds move across long expanses of warmer lake water, providing energy and picking up water vapor, which freezes and is deposited on the leeward shores. " wiki

To be sure I am going way beyond the question, but I still think it is a interesting topic. The transfer of cold or heat in water. Because that does have so much of an effect on our weather. In fact it is the melting of the ice in the water at the poles that is having so much of an effect on our weather.

 

[Strathos]

Cold is just the absence of heat.

 

[metherion]

Another thing to elaborate slightly on what Michael said is that stagnant water is not the best conductor of heat in the world. Normal the phrase 'stagnant water' evokes images of puddles with nasty things growing in them, but unstirred water in a glass is stagnant as it has no current or flow.

The ice itself will also not change temperature until it is fully melted (which may seem obvious, but it is worth mentioning), and will bring the temperature of the water around itself to the freezing point as it absorbs energy from the surrounding water to start melting. Ice just steals heat from the surrounding water until it melts, and the water around the ice can't increase in temperature past freezing because the ice will just immediately steal any heat it comes into contact with.

Since there is no flow, this pocket of cold water around the ice will have to heat up very slowly, as the water at the top absorbs just a little heat from the middle, which very slowly works its way up to the ice. Then the water in the middle starts getting a little cold, which steals just a little heat from the bottom of the glass, which again slowly works its way to towards the top.

But, as Michael said, stirring it brings more water molecules into contact with the ice- and these newly-contacting-the-ice water molecules will have more energy to give to the ice than the cold water that used to be touching the ice, which will make the rest of the water colder and melt the ice faster.

Also, the rate of heat transfer between to surfaces (like the ice and the water) increases the higher the temperature difference. So stirring to bring the warm water in your glass into contact with the ice will chill the water faster because of the higher temperature difference between the ice/warm water and the ice/already cooled water.

Just in case you were interested in a little bit of elaboration.

Metherion

 

[Justatruthseeker]

Hey everyone. I have done this ever since I can remember. When I get a glass of water or soda or whatever and it is not cold enough I will put ice in it and then stir the ice around with my finger tip. Within a few seconds, the water or whatever I am drinking becomes colder than it was prior to stirring. Why does stirring the ice make the drink colder faster?

Actually stirring warms the ice as its molecules interact with the water molecules. This causes some of the ice to melt and mix with that in the glass. It does not spread its coldness to the water it mixes with, Instead the heat in the warmer molecules is spread to the colder ones. Like hypothermia. It is you that looses heat to the cooler surrounding medium, be it air or water.

Eventually the glass of ice water will absorb heat from the surrounding air and settle to room temperature. The water simply transfers heat faster to the ice, than the air transfers it to the water. The surrounding water is simply radiating away its heat to equalize with whatever it is in contact with, Stirring it simply mixes the warmer ones with the colder ones, speeding up the process.

 

[CabVet]

Actually stirring warms the ice as its molecules interact with the water molecules. This causes some of the ice to melt and mix with that in the glass. It does not spread its coldness to the water it mixes with, Instead the heat in the warmer molecules is spread to the colder ones. Like hypothermia. It is you that looses heat to the cooler surrounding medium, be it air or water.

Wrong, the heat exchange goes both ways. Ice does change its temperature faster than water though, but I am sure you have no idea why.

Eventually the glass of ice water will absorb heat from the surrounding air and settle to room temperature. The water simply transfers heat faster to the ice, than the air transfers it to the water. The surrounding water is simply radiating away its heat to equalize with whatever it is in contact with, Stirring it simply mixes the warmer ones with the colder ones, speeding up the process.

Wrong again, transmission of heat in the water (or between water and air) is not through radiation, but through convection. The reason why the exchange is bigger between water and ice is simply because more of the surface of the ice is in contact with more water (if the ice is floating on the surface with most of it submerged). Stirring facilitates convection, so it accelerates heat transfer.

You really should stop making stuff up. There is people that actually figured out those things decades ago.