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

AI Thread Summary
The discussion centers on calculating the lung volume of a marine mammal diving to 200 meters, with an initial lung volume of 7 liters at sea level. The calculated volume at depth is 0.344 liters, but there is confusion regarding unit conversions and pressure measurements. Participants clarify that the discrepancy arises from not converting pressure units consistently between kPa and MPa. The original poster is encouraged to show their calculations to identify any errors in their approach. The conversation emphasizes the importance of unit consistency in physics problems.
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
 

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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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