You cook a meal in a 30 cm diameter pot.
The total mass of the pot and the food is 8 kg.
You let the food cool to 20 deg C.
Assuming that the lid is well fitting, no air enters the pot during the cooling period.
when you pull up on the lid, is the lid going to open or is the pot going to get stuck to the lid?
2007-07-15 07:08:15 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
We must assume that the lid let gases flow out while cooking or else the pot would have exploded. E.g. a pressure cooker vents a lot of steam. And the problem states that no air enters during cooling.
So at the end of the cooking the gas inside the pot is more or less 100% steam. Once cooled, the steam condenses leaving a vacuum. How good is the vacuum? Well it is probably in the ball park of the partial pressure of water vapor at 20 deg. C. I believe that it is less than 40 torr which is less than 1 psi.
So, yes the lid will stay on. You should be able to lift a couple hundred pounds before it comes off.
2007-07-15 08:07:55 · answer #1 · answered by Tom H 4 · 0⤊ 0⤋
Due to the cooling of the food inside the pot, it will lost some of the acquired energy during heating period. So, there is a vacuum force sucking the lid down into the pot. Therefore, the lid is going to stucked.
2007-07-16 11:01:57 · answer #2 · answered by dongskie mcmelenccx 3 · 0⤊ 0⤋
I have a large stainless steel kettle with very fine finished surfaces where the lid and kettle make contact.
We like to use it for steaming ears of corn, and every time we use it, after we remove the ears of corn, if the lid is put back on the kettle before the kettle is allowed to cool, the lid will not be able to be removed after it does cool.
We have to either put it back on the stove and reheat it, or pry the lid loose with a screwdriver.
I used to always have fun with this if we had guests that were not familiar with how and why the lid would stick.
It is also fun to fill one of those clear plastic water bottles with very hot tap water, and then dump the water out and quickly put the cap on tightly.
After about 30 seconds to a minute after replacing the cap, the air in the bottle will cool and the bottle will start to collapse, and it can produce some very strange noises as it collapses. By that time you can be out of the room and evreyone will wonder what is happening to the bottle.
The plastic used for making the bottles is very thin.
We found this out by accident one evening after rinsing several of the bottles out with very hot tap water and then recaping them and putting them in a cabinet. They actually scared us when they started collapsing.
2007-07-15 21:56:55 · answer #3 · answered by gatorbait 7 · 0⤊ 0⤋
If no air leaves the pot while heating, the lid will come right off after it has been cooled.
2007-07-15 14:40:47 · answer #4 · answered by Scott S 4 · 0⤊ 0⤋
If air was allowed to escape durring cooking, but not cooling, you would be able to figure it out if you had been given the temperature of the food when hot.
2007-07-15 14:38:03 · answer #5 · answered by carljosephchandler 2 · 0⤊ 0⤋
too many unknowns
How hot do you cook the food?
Does the lid prevent air from escaping when cooking?
2007-07-15 14:22:03 · answer #6 · answered by B 4 · 1⤊ 0⤋