Summary

First law: \Delta U=Q+W
Q is heat added W is work done
Internal energy U is the sum of kinetic energy and potential energy. Ideal gas has no internal potential energy, so solely kinetic.
Ideal monatomic gas has formula: U=\frac{3}{2}Nk_BT=\frac{3}{2}nRT
Work done on gas by external pressure: W=-P\Delta V
Negative sign means expansion does negative work on gas.
On a PV graph, integrals are work done, and straight lines are isotherms.
Four special processes:
- Isovolumeric W = 0
- Isothermic \Delta U = 0 For an ideal gas
- Isobaric W=-P\Delta V
- Adiabatic Q=0