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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The coffee around the ice will cool as heat is absorbed by the ice. The rate of transfer depends on the temperature difference, so as it cools, the coffee melts the ice more slowly. Stirring the coffee brings the average temperature near the ice up, melting it faster. Ideally you would pour hot water over the ice, so that the water that is cooled by the ice flows away and you maintain as large a temperature difference as possible over the surface of the ice.
Heat transfer via a moving fluid is known as convection, as opposed to conduction, which is heat transfer through a material, like within the ice itself.
Melting the ice takes energy, which cools the coffee. Stirring simply causes the ice to melt faster, and therefore cool the coffee down. So when the ice is melted, the temperature will be the same, ignoring the ambient air. However, typically you consume iced drinks with the ice in them, and don’t wait till it melts. So stirring leads to a colder drink.
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