a) Immediately add cold milk and then wait five minutes before drinking
b) Add cold milk at the last moment before drinking
Solution. Posted on Saturday, November 22, 2014.
According the Newton’s Law of Cooling, the rate of change of the temperature is proportional to the difference between the temperature of the body and the ambient temperature. Therefore, if milk is not added immediately, the temperature difference is bigger and coffee will cool faster. Finally, we should add cold milk at the last moment before drinking.