During an isothermal process, at 900F, the pressure on 9 lb of air drops from 85 psia to 10 psig. For an internally reversible process,

A cylinder-piston apparatus contains 29 kg of air at 30°C. Weights on the piston fix the initial pressure at 20 bar. Find the work done if: a. Some of the weights are quickly removed until external pressure is 5 bar. The temperature remains constant. b. Some of the weights are slowly removed until the external pressure reaches 5 bar. The temperature remains constant. c. The expansion from 20 bar to 5 bar is polytropic, with an exponent of 1.4. Note that if the gas is ideal and PV = constant, then the temperature varies as: T₂ Tv 1-n P. n-1

Either solve all parts or leave it unsolved ... I vll upvote