A cylinder has two sides containing gas and water separately

AI Thread Summary
The discussion revolves around a cylinder containing gas and water, highlighting the complexities of fluid pressure at varying depths. Participants emphasize the importance of considering net forces on each side of the piston, which cannot rotate due to its thickness. A specific scenario is presented where water is drained at a constant rate, prompting a calculation for the necessary cooling rate of the gas to maintain the piston’s position. An alternative approach suggested involves calculating the time required for the water container to empty, focusing on keeping the gas volume constant during this process. The conversation underscores the interplay between fluid dynamics and thermodynamics in this scenario.
highschoboy004
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Homework Statement
A rectangular cuboid is made up of two identical cubes which have side length a = 10 cm. The cubes are separated by a frictionless piston of negligible mass in the middle. The cube on the left contains gas which has initial temperature of 27 degree Celsius and initial pressure 4x10^5 N/m2. The cube on the right is full of water. We then open the valve to drain the water at a constant rate of 10cm3/s, if we are to keep the piston still then at what rate must we lower the gas temperature (°C/s)(using the heat regulator)?
Relevant Equations
nRT=pV
I think this problem is somehow weird since fluid has different pressures at different depths. cylinder.png
 
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highschoboy004 said:
I think this problem is somehow weird since fluid has different pressures at different depths.
You can assume the piston has some thickness so that it can’t rotate. So you only have to consider the net force each side. How it is distributed across the piston surface does not matter.
 
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haruspex said:
You can assume the piston has some thickness so that it can’t rotate. So you only have to consider the net force each side. How it is distributed across the piston surface does not ma
Thanks a lot<3, I'm on my way with the numbers
 
highschoboy004 said:
The cube on the right is full of water. We then open the valve to drain the water at a constant rate of 10cm3/s, if we are to keep the piston still then at what rate must we lower the gas temperature (°C/s)(using the heat regulator)?
Relevant Equations: nRT=pV
Welcome!

Another approach, which may bypass the weirdness of the problem regarding different pressures at different depths, is calculating the time for the water container to get empty.

The rate of cooling of the gas must be such that the physical volume that it occupies (under steady decreasing external force or pressure tending to zero) should remain constant at least within that period of time.
 
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Lnewqban said:
Welcome!

Another approach, which may bypass the weirdness of the problem regarding different pressures at different depths, is calculating the time for the water container to get empty.

The rate of cooling of the gas must be such that the physical volume that it occupies (under steady decreasing external force or pressure tending to zero) should remain constant at least within that period of time.
Thanks, it does help a lot!!
 
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