Thread: HOT COFFEE

To drink a coffee at the hottest possible temperature, should you add the creamer once or only when you are ready to drink it?

Tfinal = Tdiff e–kt + Tsurroundings

You would drink it right away before it cools off.

yeh i had this question at an interview and it hink he phrased it wrong.

the question should be. women gets a cup of coffee, doesnt want to drink it for 10 minutes but wants it to be hot as possible, should she add the R.T milk straight away or wait 10 minutes then add it

Add the milk early.

Originally Posted by Harold14370

Add the milk early.

why? is the milk cold or hot?

Originally Posted by evariste.galois

Originally Posted by Harold14370

Add the milk early.

why? is the milk cold or hot?

To answer the question, you need to make a few assumptions, like it's ordinary coffee in and ordinary cup in an ordinary room and you are putting ordinary (cold) milk in it. The reason you add the milk early is because the rate of cooling is proportional to the difference in temperature between the coffee and the outside air.

Forgot the potentially standing (warming?) cream.

mmh, lets see if i got this right (obviously not :wink: )

if you do not add the milk to the coffee, you start out with a high temperature and a high rate of cooling. subsequently, the coffee will become colder and eventually the rate of cooling will decrease as well, right?

the coffee with the milk will start with a lower temperature and a lower rate of cooling.

i would then say that the coffee without milk will "catch up" but will never be colder than the one with the milk. But, in the end you have to add the milk to the first cup of coffee, which decreases the temperature and you end up with a colder coffee.

is it actually never a question of time?

Originally Posted by Pong

Forgot the potentially standing (warming?) cream.

You are right about that, but I'm thinking the heat gained by the milk will be small compared to the heat lost by the coffee. The initial temperature difference to ambient would be about 30 F for the milk vs 140 for the coffee, and the mass is much less.