Heat Cycles, Work, and Efficiency

[Marcin H]

Homework Statement

Homework Equations

W=-∫PdV
ε=W/Q
PV=nRT
COP=Q/W

The Attempt at a Solution

Using the first equation for work, I got W=-nrT*ln(3V1/V1) but I don't think that is right. Is this the wrong formula to use for this problem? My answer should be in terms of P1 and V1.

 

[Chestermiller]

That is not the correct integration of PdV for the process shown in the figure.

 

[Marcin H]

That is not the correct integration of PdV for the process shown in the figure.

What equation can I use to find the work then?

 

[Chestermiller]

What equation can I use to find the work then?

You can use the integral of PdV. Just do it in a way that is consistent with what you see in the diagram.

 

[Marcin H]

You can use the integral of PdV. Just do it in a way that is consistent with what you see in the diagram.

I just took the area of the rectangle. So W=2P1V1. I got an efficiency of 17% with that.