P-V Diagram: Computing Work and Determining Sign of Work

[Saladsamurai]

Homework Statement

I have plotted the info as such

I can compute the work by adding the area of the triangle to the area of the rectangle, but my question is is all of this work negative? It is compressed so I am assuming it is?

 

[alphysicist]

Hi Saladsamurai,

Is your book asking for the work done by the gas, or the work done on the gas?

 

[stewartcs]

Homework Statement

I have plotted the info as such

I can compute the work by adding the area of the triangle to the area of the rectangle, but my question is is all of this work negative? It is compressed so I am assuming it is?

I can't see your diagram while I'm at work, however, based on what you wrote if the dV is negative, then the boundary work will be negative. If the dV is positive, then the boundary work is positive. Remember that P is absolute pressure and is thus always positive.

$$W_b = \int_1^2 PdV$$

Like alphysicist eluded to, it may be written as a positive value based on the convention taken.

CS