[ELI5] how does ice melt faster/more stirred than just sitting?

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For instance, I make myself some hot coffee and I want to turn it to iced coffee. Stirring it seems to cool it down much faster than letting the ice just sit in the coffee, however, from what I have read, stirring the ice melts the ice faster and more even though it cools it down faster. Why? Is this even correct?

Also, would the ice just sitting in the hot coffee melt roughly the same amount as the stirred once the coffees reaches the desired cold temperatures? Idk we can make one up, coffee from 160°f to 40°f, I guess. I also generally fill my coffee cup completely with ice as I’m sure the amount of ice changes this.

I hope this makes sense and I tagged the question correctly. Thank you,

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13 Answers

Anonymous 0 Comments

Heat flows from hotter to colder, with the rate of transfer proportional to the difference in temperature. A larger difference in temperature, a faster heat transfer, in this case more cooling of the coffee. Now if the coffee is just standing still, the coffee just adjacent to the ice cube will be colder than the rest of the coffee, so the heat transfer will be slower. There will be less cooling. If you are constantly stirring the coffee, then hot coffee will always be in contact with the ice cube and the heat transfer will be faster, the coffee will cool down faster. It is exactly the same reason why in hot weather you cool down faster in front of a fan than in still air.

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