Where do potatoes boil the fastest?

A pot of potatoes is put on the stove on a mountain and at sea level. Where will they boil first?

The boiling point of water depends on air pressure and the surroundings. The pressure at sea level makes water boil at a temperature of 100 degrees C. On a mountain peak, the pressure is lower, and so is the boiling point of water.

That is so because water molecules can more easily escape the water surface of the pot, when the atmospheric pressure pushes less "on to" the water. So, water will evaporate faster at a lower pressure – a process known as boiling. In principle, water could boil at room temperature, if the air pressure were sufficiently low.

However, potatoes are not cooked just because the water boils. The root crop requires a high heat supply to be thoroughly cooked. Having reached the boiling point, the water temperature does not rise any further, and so, the potatoes will not get as much heat- energy per minute on the mountain.

This means that potatoes cook (by boiling) faster at sea level, even though it will take a tiny bit longer to bring them to the boil.

Water boils faster in thin mountain air, but lower water temp means food takes longer to cook.