Does blood plasma height need the container area to find minimum height above a vein?

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acgold
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Maybe I'm missing something here but wouldn't I need the area to solve the following problem?

1. Blood plasma has a density of 1026 kg/m^3. What is the minimum height above a vein -- in which the blood pressure is 16 torr -- that a container of blood plasma should be placed in order for the plasma to enter the vein?
The answer given is h=21 cm.

Don't I need more information to solve this? eh, my brain is fried. Help :smile:
 
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This is just another hydrostatic pressure / water column problem. I think the assumption they're making is that you want to place the blood bag high enough (h) so that the pressure of the plasma in the IV tube ([tex]\rho g h[/tex]) equals 16 torr when the tube enters the vein (at the "bottom" of the tube). If the pressure at the end of the tube is lower than 16 torr, blood is going to come out of the vein. If the pressure is greater than or equal to 16 torr, the plasma in the tube should be able to flow into the vein.
 
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Yes, you are correct. To solve this problem, we would need more information, specifically the area of the vein where the plasma will enter. Without the area, we cannot calculate the volume of plasma that will enter the vein, and therefore cannot determine the minimum height above the vein. It is possible that the problem is missing some information or there may be a typo. I would suggest double checking the problem or asking for clarification from the source.