The Gas Keeps Count of Every Joule

You'll learnwhich way the sign of W points, why the endpoints fix ΔU while the route fixes Q and W, and how to read work off a PV diagram as the area under the path.

Squeeze a gas and it warms with no flame anywhere near it. Walk it around a loop on a PV diagram and it comes home unchanged, having turned 800 joules of heating into work. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · THE SIGN OF W · STATE VERSUS PATH · AREA IS WORK · v2

squeezing adds energy · ΔU from the endpoints, work from the area

Before you start

What you're looking at

A cylinder of gas whose piston can be pushed in or out, and then the pressure against volume map of its states.

The question

When energy enters by heating and by pushing, what does the gas keep, and which parts depend on the route?

Step 1 / 12