Thermodynamics, Statistical Physics, and Quantum Mechanics

116 SOLUTIONS

The total energy of the idealgas depends only on thetemperature,which
is constant, so the heatabsorbed by the gas is

i.e., heatis rejected from the gas into the reservoir. Alternatively,since

the sameresult as in (S.4.25.3).

For an adiabatic expansion theentropy isconserved, so

On theotherhand,

where isthe specificheat for an ideal gasat constant volume. From
(S.4.25.5) and(S.4.25.6), andusing the ideal gas law, weobtain

b)