[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

You are absolutely right, stirring does speed it up 🙂
Let’s look at why:

First, I’m sure you’ve heard this before but “energy cannot be created or destroyed”, so in order for the ice to heat up and melt it needs the coffee to cool down. So by making the ice melt faster you are necessarily cooling the coffee faster. The heating of the ice is connected directly to the coffee cooling.

It’s like a convection oven. When stirred, the heat transfers faster, which melts the ice faster, which in turn cools the coffee because of the connection.

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