Physics IA: Water cooling

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About this paper

The Internal Assessment, or IA, is a required component of the International Baccalaureate Diploma Programme for high school students in several subject areas. This essay was submitted by Marius Lindvall for evaluation for the May 2017 examination session. The grade awarded to this paper was 7, scoring 20 marks out of 20.


The goal of this investigation is to determine which means of cooling is the most efficient for cooling down a cup of boiling water. The idea for doing this investigation came about from the everyday situation of drinking tea and/or coffee that is too hot. Boiling water will cause damage to the mouth and throat if one attempts to drink it without cooling it down first. Studies have shown that 60 °C is the optimal temperature to consume hot beverages (Brown & Diller, 2008; Lee & O’Mahony, 2002). However, cooling the water down to this temperature can involve a lot of waiting, something which can be unwanted if one is in a hurry, or if the person drinking the coffee or tea wants to enjoy the beverage as soon as they can after making it. By comparing different means of cooling, this experiment identifies the most efficient cooling method to effectively solve the real-world issue presented above.

The experiment focuses on cooling methods which may be considered practical and also socially acceptable to perform in the context of cooling a cup of tea or coffee. As such, focus is primarily put on different ways of stirring, although some other cooling methods are used as well. Some cooling methods, such as lowering the cup into a box of liquid nitrogen, are considered very effective, but not practical to perform, so they have been omitted. Putting ice cubes into the water was also considered as a cooling method, but was omitted because it can be difficult to stop the cooling by the time the water reaches the desired temperature, and it is vital that the beverage is not too cold when consumed.

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