Change in a marine mammal's lung volume when diving to 200 meters

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Homework Help Overview

The discussion revolves around the change in a marine mammal's lung volume when diving to a depth of 200 meters, considering the effects of pressure and temperature on gas volume. The problem involves understanding the relationship between pressure and volume, as well as unit conversions.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the calculation of lung volume at depth, questioning the conversion of units from liters to cubic meters. There is also discussion about the correct interpretation of pressure units and their impact on the calculations.

Discussion Status

The discussion is active, with participants providing insights into potential errors in unit conversion and the derivation of the equation used. Some participants express confusion about the correctness of the answer provided and seek clarification on the calculation process.

Contextual Notes

There are mentions of differing pressure units (kPa and MPa) that may affect the calculations, and participants are encouraged to ensure consistency in units. The original poster's attachment is referenced, but its clarity is questioned.

crystal1001
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Homework Statement
A marine mammal holds its breath and dives 200 m below the sea surface, where the total pressure is 2.061MPa. The volume of the mammal’s lungs when fully inflated at sea surface (air pressure = 101.3kPa) is 7 L. Assuming that the mammal’s core temperature remains constant at 310K, what will the volume of its lungs be when it reaches a depth of 200 m?
Answer: 0.344 litre
Relevant Equations
v^2=P1V1/P2
I attempt the solution on the attachment. The answer is 0.344 litre. Do I change 7L to m, so it is 0.007 cubic meters
 

Attachments

  • 20191106_003343.jpg
    20191106_003343.jpg
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crystal1001 said:
Homework Statement: A marine mammal holds its breath and dives 200 m below the sea surface, where the total pressure is 2.061MPa. The volume of the mammal’s lungs when fully inflated at sea surface (air pressure = 101.3kPa) is 7 L. Assuming that the mammal’s core temperature remains constant at 310K, what will the volume of its lungs be when it reaches a depth of 200 m?
Answer: 0.344 litre
Homework Equations: v^2=P1V1/P2

I attempt the solution on the attachment. The answer is 0.344 litre. Do I change 7L to m, so it is 0.007 cubic meters
I do not understand your difficulty. You seem to have the answer. Are you saying 0.344L is wrong?
Why would you want to convert to m^3?

PS. In future, please use more meaningful thread titles.
 
In saying the answer is 0.344 l I believe you are saying that you have been given a correct answer but need to figure out how that was calculated, correct?

And I believe your concern is that you got 344 instead of 0.344, correct? I think your only problem is that you ignored that one pressure was in kPa and the other is in MPa. That’s why you are off by 3 orders of magnitude. Put the pressures in the same units.
 
Could you show how you derived this equation? I think there is a problem there.

Homework Equations: v^2=P1V1/P2
 
Cutter Ketch said:
And I believe your concern is that you got 344 instead of 0.344
Ah! The image was so faint I assumed the period was just invisible.
 
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Tom.G said:
Could you show how you derived this equation? I think there is a problem there.

Homework Equations: v^2=P1V1/P2
Clearly it is a typo for v2=P1V1/P2 (which is what the OP used).
 
Tom.G said:
Could you show how you derived this equation? I think there is a problem there.

Homework Equations: v^2=P1V1/P2
I think that is just a typo. It is correct in the attached image
 

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