Thermodynamic system

Big use of PV diagrams. The area under the increase of volume is work done.

First law

$Q=\Delta U+W$ On the PV diagrams: isovolumetric for volume and isobaric for pressure.

Adiabatic processes

Occurs so fast there are no exchanges in heat. Crosses temperatures.

Efficiency

Normally, its $\frac{W}{Q_{hot}}=1-\frac{Q_{cold}}{Q_{hot}}$ In carnot, which is the maximum efficiency, the gas does work and cools down, the max efficiency is $1-\frac{T_{cold}}{T_{hot}}$ since $T\propto Q$.

Entropy