Q4: A piston--cylinder device containing argon gas as the system undergoes an isothermal process from 200 kPa and 100°C to 50 kPa. During the process, 1500 kJ of heat is transferred to the system. Determine the mass of this system and the amount of work produced.

Determine the efficiency for the cycle (standard air used as the working fluid) indicated in the sketch. Assume the pressures and temperatures are known quantities at each state. 1-2 constant volume process and 2-3 constant pressure process.

May I ask if a block of copper falling into a tank filled with water is considered a closed or open steady system?