Thermodynamic and an organic matter

[appplejack]

Homework Statement

I was given and writing assignment which requires me to write a two-page report on how an organic matter like a potato can exist according to the Laws of Thermodynamics. I will be evaluated on how well I explain scientific principles and how accurate my statements are. The report should be comprehensible by non-scientists. This course require no math like calculus. I think this is a physics course for non physics major or minor

Homework Equations

The Attempt at a Solution

I think a organic matter like a potato is structured and I think I should think about entropy and its relationship with the potato. It keeps losing its heat and energy and at one point will start decaying and will be devoured by microorganisms and become dust or a part of soil. Given the amount of information I know for now won't be enough to write 2 pages on this thought experiment. I'd like to ask for some more insights to be able to finish this report. Thank you very much.

 

[Andrew Mason]

Homework Statement

I was given and writing assignment which requires me to write a two-page report on how an organic matter like a potato can exist according to the Laws of Thermodynamics. I will be evaluated on how well I explain scientific principles and how accurate my statements are. The report should be comprehensible by non-scientists. This course require no math like calculus. I think this is a physics course for non physics major or minor

Homework Equations

The Attempt at a Solution

I think a organic matter like a potato is structured and I think I should think about entropy and its relationship with the potato. It keeps losing its heat and energy and at one point will start decaying and will be devoured by microorganisms and become dust or a part of soil. Given the amount of information I know for now won't be enough to write 2 pages on this thought experiment. I'd like to ask for some more insights to be able to finish this report. Thank you very much.

It requires energy to build a potato. The sun's radiant energy is absorbed by the potato leaves. This allows the cells in the potato leaf to convert carbon dioxide in the air into complex hydrocarbon molecules which it stores in its roots, thereby creating the potato. This is a thermodynamic process since the distribution of energy from the sun follows a temperature curve (a Maxwell-Boltzmann distribution). You can think of the energy absorbed by the plant to make the potato as heat flow.

Since the potato plant gains heat flow at an ambient temperature T, which would be a bit above 273K, what can you say about the change in entropy of the potato plant?

What is the temperature of the sun? What is the change in entropy of the sun due to the heat flow out of the sun that is transferred to the plant? How does that compare to the change in entropy of the potato plant?

What does the second law of thermodynamics say about the total change in entropy of the universe in any thermodynamic process? Is that law kept in this case?

AM

 

[appplejack]

Thanks Andrew.

It requires energy to build a potato. The sun's radiant energy is absorbed by the potato leaves. This allows the cells in the potato leaf to convert carbon dioxide in the air into complex hydrocarbon molecules which it stores in its roots, thereby creating the potato. This is a thermodynamic process since the distribution of energy from the sun follows a temperature curve (a Maxwell-Boltzmann distribution). You can think of the energy absorbed by the plant to make the potato as heat flow.

Since the potato plant gains heat flow at an ambient temperature T, which would be a bit above 273K, what can you say about the change in entropy of the potato plant?

What is the temperature of the sun? What is the change in entropy of the sun due to the heat flow out of the sun that is transferred to the plant? How does that compare to the change in entropy of the potato plant?

I think say the entropy of the potato plant decrease because it absorbs radiation from the sun. Whereas the entropy of the sun will increase. The sun emits heat and the some of the heat gets absorbed by the planet Earth but some of it gets lost in its way to the earth.

What does the second law of thermodynamics say about the total change in entropy of the universe in any thermodynamic process? Is that law kept in this case?

The second law of thermodynamics states that heat flows from hot area to cold area until there's a equilibrium.

Please let me know. This course I am taking is kind of haphazard. I'm not in physics but
I'm going into Physics major program next year. This course is an elective. Thank you for your help. Frankly it's going to be a struggle for me to fill 2 pages for my report. I will keep posting whenever I find something new to me.
Thanks.

 

[appplejack]

On second thought, I think entropy increases for the sun and almost remains the same for the potato until it dies.

 

[Andrew Mason]

I think say the entropy of the potato plant decrease because it absorbs radiation from the sun. Whereas the entropy of the sun will increase. The sun emits heat and the some of the heat gets absorbed by the planet Earth but some of it gets lost in its way to the earth.

Use dS = dQ/T where dQ is positive if heat flow is into the body and negative if it flows out of the body. Don't concern yourself with the heat flow out of the sun that is not absorbed by the plant.

The second law of thermodynamics states that heat flows from hot area to cold area until there's a equilibrium.

True. But what does it say about the change in entropy of the universe in any thermodynamic process?

AM

 

[Andrew Mason]

On second thought, I think entropy increases for the sun and almost remains the same for the potato until it dies.

What is dS = dQ/T for the sun? Is dQ positive or negative? Does the potato continue to experience heat flow into the plant so long as it is converting the sun's energy into chemical (food) energy in building the potato? What is dS = dQ/T for the potato? How does that compare to dS for the sun? (note: consider the case where |dQ| for the plant = |dQ| for the sun) ?

AM

 

[appplejack]

Use dS = dQ/T where dQ is positive if heat flow is into the body and negative if it flows out of the body. Don't concern yourself with the heat flow out of the sun that is not absorbed by the plant.

True. But what does it say about the change in entropy of the universe in any thermodynamic process?

AM

The entropy in the universe increases always. Because the universe is a closed system.
New order may rises in different forms like a beginning of a potato plant within this closed system. So there is tremendous but finite amount of energy available in the universe. But last time I heard the universe is expanding. How does this fit into this?

 

[Andrew Mason]

The entropy in the universe increases always. Because the universe is a closed system.
New order may rises in different forms like a beginning of a potato plant within this closed system. So there is tremendous but finite amount of energy available in the universe. But last time I heard the universe is expanding. How does this fit into this?

That's a different question for a different thread. Try the Cosmology board for that.

AM