## Essential University Physics: Volume 1 (3rd Edition)

We first find the internal energies of each of the gases: $E_{intO_{2}}= \frac{5}{2}nRT=5RT$ $E_{int_{Ar}}= \frac{3}{2}nRT=1.5RT$ Adding the internal energies, we find: $C_v=\frac{6.5RT}{nT}=\frac{6.5R}{3}=2.2R$