How Do You Solve Adiabatic Process Problems Involving a Piston and Sand?

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Homework Help Overview

The discussion revolves around an adiabatic process involving a piston and a monatomic ideal gas within an insulated cylinder. The scenario includes the gradual addition of sand onto the piston, affecting the gas's behavior and state. Participants are exploring the implications of this setup in the context of thermodynamics.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants are considering the relationship between the work done by gravity and the work done by the gas. There are questions about the validity of equating these works and the implications of the adiabatic process on internal energy. Some are also questioning the classification of the problem as a physics or chemistry issue.

Discussion Status

There are multiple interpretations being explored, with some participants attempting to confirm calculations related to the mass of the piston and the gas. Guidance has been offered regarding the use of work-energy principles in the context of adiabatic processes, though no consensus has been reached on specific methods or outcomes.

Contextual Notes

Participants are navigating the complexities of the problem, including assumptions about heat exchange and the gradual addition of mass to the system. The discussion reflects a mix of uncertainty and exploration of thermodynamic principles.

sheyshaw
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An insulated cylinder of cross-sectional area .010m2 contains a monatomic ideal gas at T= 280 K. The system is in a vacuum chamber. Initally the gas supports the piston at a height of .20m. Sand is slowly placed onto the piston. When 10 kg of sand has been added, the piston has fallen .05m. How much gas is in the cylinder? what is the mass of the piston?

Im having difficulty getting started

Can i equate the work done by gravity with the work done by the gas?
 
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Isn't this more of a chemistry problem? There's another thread for chem.; you might have more luck over there.
 
No its right out of a physics book! Its a thermodynamics problem
 
Im getting 66.34 kg can someone confirm this
 
Ouch. My bad.
 
sheyshaw said:
Im getting 66.34 kg can someone confirm this
Explain your work and we will review it.

AM
 
Review this:

I plan to solve the problem using the fact that the work done by gravity on the gas will equal the change in internal energy.

I reason this because Q = u + W

The process is adiabatic so u = -w

does that work?
 
sheyshaw said:
Review this:

I plan to solve the problem using the fact that the work done by gravity on the gas will equal the change in internal energy.

I reason this because Q = u + W

The process is adiabatic so u = -w

does that work?
How do you calculate the work done by gravity? The sand is gradually adding to the weight as the gas is compressing.

You can determine the final volume of the gas. You can assume that no heat is exchanged with the environment, so it is adiabatic. I would use the adiabatic condition to determine the final temperature.

AM
 

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