# Water boiling and cooking time

Will there be a difference in the time for which it will take for eggs to be prepared in the cases mentioned below?

A. Cooking eggs in a pot on full gas power until the water reach boiling point - and then lowering gas to mimimum power.

B. Cooking eggs in a pot on full gas power until the water reach boiling point - and then leaving gas maximum power.

Question rephrased: in which case will the eggs be prepared faster?

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## migrated from physics.stackexchange.comJul 24 '13 at 19:06

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My guess: As long as the water keeps boiling (during the second phase of both A and B), its temperature will remain (roughly) the same, no matter how much gas is used. So, A and B should have the same result. But, I would gladly see a refutation of this. – Gugg Jul 23 '13 at 21:26
The way I cook eggs, you don't even have to keep the water boiling. That is, I heat the water with the eggs inside and thus heat the eggs uniformly, then I turn off the stove and let them sit. It would be good to check how thoroughly cooked the eggs are at that point, when the water just boils. They might be done already. – krs013 Jul 23 '13 at 22:09
Is this not a straight forward heat transfer from one medium to another question? Just because it deals with food doesn't mean it's not a physics question. – tpg2114 Jul 24 '13 at 19:01
From a cooking point of view, you don't want to cook eggs too fast. The longer you make their cooking, the better tasting results you get. – rumtscho Jul 24 '13 at 20:26
Very related: cooking.stackexchange.com/questions/27745/… - the difference being that that question asks about slow vs fast boil, while you ask about low vs high power, and your low power may or may not actually be boiling. – Jefromi Jul 24 '13 at 21:09

As long as the water is actually boiling the whole time, then there is no difference whatsoever.

Boiling water can only have one temperature (around 100 C, but adjusted somewhat for altitude or impurities in the water), and it stays at that temperature as long as it's in a state of boiling. Keeping the heat up only serves to hasten the transition from water to steam.

The heat transferred into the eggs (or whatever you are cooking) depends only on the temperature of the water, not on the vigor with which it is boiling. As a result, keeping the gas on high will generally have two effects: (1) wasting more gas by heating up the room more and turning more water into steam than necessary, and (2) increasing the chances that the eggs will be tossed around enough to crack. On the other hand, if you turn the gas so low that the water is no longer truly boiling, its temperature will drop below the boiling point, slowing the cooking process (and possibly even changing the end result - cooking is a complicated chemical process that relies on the right amount of heat being applied over the proper length of time).

Of course, there are cases where a recipe may call for a particular level of boiling, but my guess is this usually has to do with keeping the food from sticking to the pot or some such thing, with vigorous boiling replacing the need for constant stirring.

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It will make no difference. Once the water reaches \$T=100^\circ C = 373 K\$ it will stay at that temperature. Water cannot go any further, while water vapor can! You could only cook your egs faster if you would cook them in a water vapor!

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... or in a pressure cooker, which raises the liquid temperature above \$100^\circ C\$ – User58220 Jul 24 '13 at 3:10