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Thermodynamics cooking Question

  • Thread starter ashkash
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1. Homework Statement

A househusband is cooking beef stew for his family in a pan that is (a) uncovered, (b) covered with a light lid, and (c) covered with a heavy lid. For which case will the cooking be the shortest? Why?

2. Homework Equations



3. The Attempt at a Solution

I dont know where to start with this question. Any help would be appreciated. thanks.
 

Answers and Replies

Andrew Mason
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1. Homework Statement

A househusband is cooking beef stew for his family in a pan that is (a) uncovered, (b) covered with a light lid, and (c) covered with a heavy lid. For which case will the cooking be the shortest? Why?

2. Homework Equations



3. The Attempt at a Solution

I dont know where to start with this question. Any help would be appreciated. thanks.
Think of the beef being cooked in water on an element that is at a temperature greater than 100 deg. C.

What happens to the water? What is the temperature of that phase of water? Which of the three ways would result in that (phase of) water reaching the highest temperature?

AM
 
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When the temperature is greater than 100 deg C the water boils and turns into vapor. To get the highest temperature in that phase the pan would need to be covered with a heavy lid. This will give the shortest cooking time.

Is this correct or am I on the right path? thanks.
 
Andrew Mason
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When the temperature is greater than 100 deg C the water boils and turns into vapor. To get the highest temperature in that phase the pan would need to be covered with a heavy lid. This will give the shortest cooking time.

Is this correct or am I on the right path? thanks.
Sort of on the right track. You haven't explained why the heavy lid will give you the shortest cooking time.

Think of the quantity of heat contained in the steam. You want to maximize the amount of heat contained in the steam. How is that be done (think of the steam as an ideal gas and set up an equation for heat in terms of temperature pressure, volume and quantity of steam)?

AM
 
125
2
When the temperature is greater than 100 deg C the water boils and turns into vapor. To get the highest temperature in that phase the pan would need to be covered with a heavy lid. This will give the shortest cooking time.

Is this correct or am I on the right path? thanks.
How does a pressure cooker work?
 
Gokul43201
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thats a very politically correct problem you have there...
 
Andrew Mason
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But the meat is submerged in the water, isn't it?
Not necessarily. But it doesn't really matter. Assuming the water and steam are in thermal equilibrium, the water will be at the same temperature as the steam.

AM
 

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