Friday, December 8, 2017

Boiling cold porridge

My friend bought a new pot and made rice porridge in the Bryan complex kitchen. I was out that night so she invited me the next day to taste the porridge.

We put pot filled with cold porridge on the stove, and after a while it started boiling in the middle. So we turned off the stove and started to taste it. However, we soon found out that the porridge near the sides of the pot was still cold.

This can be explained using the concept of viscosity. When the rice porridge is cooled in the fridge, it became a jelly-like substance with great viscosity. As we put the pot on the stove, the fire under the pot only heated the part of porridge directly above the fire. Because of it's great viscosity, the porridge  hardly flow around, resulting in it also having very limited heat conductivity. In this case, porridge near the rim of the pot can still be cold, when the centre is already boiling.

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