Physics problem.Only logic,no formulas.

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Discussion Overview

The discussion revolves around the phenomenon of boiling water in a dish after pouring cold water on the outside. Participants explore the conditions under which this might occur, the implications of atmospheric pressure, and the materials involved.

Discussion Character

  • Exploratory
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests that boiling could restart if the water is near boiling and a local low pressure is created by pouring cold water outside the dish.
  • Another participant questions the feasibility of this happening and expresses skepticism about the initial claim.
  • A participant highlights the importance of atmospheric pressure on boiling temperature, noting that it varies with altitude and weather conditions.
  • There is a query about the reliability of the experiment, asking if it is repeatable or a one-off occurrence.
  • One participant speculates whether thermal contraction of a metal dish could create more nucleation sites for boiling.
  • Another participant requests additional details about the experiment, such as the type of oven used and the material of the dish, to better understand the situation.
  • A participant states that while cooling the outside of a container does not generally cause boiling, it may under specific conditions, referencing a YouTube video for further context.

Areas of Agreement / Disagreement

Participants express differing views on whether pouring cold water on the outside of the dish can restart boiling. Some propose conditions under which it might occur, while others remain skeptical, indicating a lack of consensus.

Contextual Notes

The discussion includes assumptions about the materials involved, the specific conditions of the experiment, and the influence of atmospheric pressure, which remain unresolved.

Elaia
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In a dish we pour water.We boil it for some moments.Then we turn off the oven and the water gets colder.The boiling is interrupted.If we pour cold water outside the dish (in contact with it) the boiling starts again.WHY does the boiling start again??
 
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It wouldn't. Why on Earth would it?
 
Is this the result of an actual experiment?

I could see it happening provided the water in the dish were very near boiling. Boiling temperature depends on the atmospheric pressure.

The lower the atmospheric pressure, the lower the boiling point of water. For example, water always boils at a lower temperature at high altitudes (and many recipes vary their quantities/procedure slightly for high altitude). If you were boiling water right before a storm hit, the water would also boil at a slightly lower temperature as the air pressure dropped.

If pouring the water on the outside of the dish created a local low pressure area over the dish, then water that was just barely below the boiling temperature could start boiling again. Of course, the dish would have to be made of a material that insulated very well, so that pouring cold water on the outside of the dish didn't immediately lower the temperature of the water inside the dish. In other words, if this did work, I wouldn't expect it to work for long.
 
I have to ask whether the experiment is reliably repeatable or a one-off.
 
Say the dish is metal - would the thermal contraction create a rougher surface and more nucleation sites?

Grasping at straws here.
 
Last edited:
I see you have used the word "oven". What kind of oven? Did you open a door to add water? What material was the lower dish made from? What was the oven temperature?
One of these details (or another) may give us a clue, I hope. Can you describe the whole thing nor fully?
 
It is not in general true that cooling the outside of a container will cause the water to boil.

However, under some restricted conditions this can happen, as Bob alluded. See the You Tube video.

 
Last edited by a moderator:
Calling mythbusters ...
 

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