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Determing the Actual Boundary Work Experimentally

We can use sensors to measure P and V.
Data of this nature is shown in the P-V Diagram, below.

Piston-and-cylinder device that illustrates pressure.

The Actual expansion of gas (or liquid)

Integrate the data numerically to obtain an estimate of W12.

Does it matter how long this process takes to complete ?

Determining work

Lesson
4A Blog

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Lesson 4A: page 13 of 31

One way to determine the path that our system follows would be to measure both pressure and volume as the process takes place.
We could install a pressure sensor inside the cylinder. We could also use a level sensor to determine the position of the piston. Then, if we measure the surface area of the piston, we could calculate the volume of the gas.
We could plot the data on a P-V Diagram, as shown here.
The path might be smooth and it might not.
But in any case we could use the trapezoidal rule to numerically integrate from V1 to V2 and thus determine the work done by the system on the surroundings.
Now, we need to get back to a point that I postponed earlier in this lesson.
Does it matter how FAST the piston moves or how long our process takes ?
Hmmm… I would guess that it does. Flip the page to see why.

Determing the Actual Boundary Work Experimentally

Ch 4, Lesson A, Page 13 - Determing the Actual Boundary Work Experimentally