Water freezing

[robheus]

Assume you have two identical cups, filled with identical water and identical amount of water. The only difference being that the water in the second cup is hot, the other room temperature.

 

After placing them in a refridgerator, which one of the cups of water will freeze first, the room temperature cup or the hot cup?

 

It seems logical to say that the cup with hot water has first to cool down (although it cools down quicker because of a higher temperature gradient as the room temperature water) to room temperature, and then it would take the same amount of time for it to freeze as the room temperature water, so it would last longer for it to freeze.

 

Simple logic, isn it?

 

But please try this yourself, and investigate the answer.

 

The answer might surprise you!

 

Here is an article on this phenomena.

Edited July 20, 2012 by robheus

[CaptainPanic]

If heat transfer would be so simple, we'd all have a much lower energy bill.

 

I think wikipedia gives a better (longer) list of possible reasons why the Mpemba effect occurs than the article you linked to.

[burhan hafiz]

it is due to the fact that the molecules of hot water lose water more easily and faster then that of cold water.

 

Edited July 22, 2012 by burhan hafiz