Why is work zero when an insulated box reaches equilibrium?

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Homework Statement



"An insulated box is initially divided by a frictionless, thermally conducting piston. One side of the piston is 1.5(m^3) of air at 400k, 4bar. The other side is 1.5(m^3) of air at 400K,2 bar
The piston is released and equilibrium is attained, with the piston experiencing no change of state"


the solution assumes W=0. why is this?

Homework Equations





The Attempt at a Solution

 

Discussion

dauto said:
What solution? You didn't post any solution.

here
 
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  • Scanned text titled ENGINEERING MODEL listing five numbered assumptions: the system is the piston and the air in the box; after release equilibrium is reached with no change in state; air is an ideal gas; the piston moves freely and is thermally conducting; W=Q=0 with no overall change in kinetic or potential energy.
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That's the work for the entire system, not the work between the two chambers. Since the entire system is in a isolated box, there is no external work or heat.
 

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