I tried searching for this but i couldn't find an answer so i hope this is hasn't been discussed and if so - sorry- and id appreciate a link.. Here we go: Lets say we have to glasses, A and B. In glass A we pour boiling water and add milk straight afterwards. Now for glass B we pour the boiling water then wait 3 min and then add the milk. Now we take temps of both. Which of the two mixtures will be hotter after the three min? Explain. My solution: We all know that the heat transfer is dependent on the temp diff - therefor the glass without the milk (B) losses more heat to its surroundings during the 3 min. But- now that we add the milk to glass B, the temperature difference is lower and the milk "cools" the water less then it cooled the hot water in A (At the beginning the temp diff was bigger). - At this point i just picked one and didn't really back up my choice, i said that it depends which is has a more crucial effect.. Question: Which has more of a effect? the higher temp between the glass and surroundings or the milk cooling that relies on the temp diff? **The milk is stirred, the same amounts and relations for A and B, the milk stays in the same temp (refrigerated).