A closed, expandable system like that shown below is operated in an adiabatic manner. First, 15,000 lb;ft of work are done by this system. Then, work is applied to the stirring device to raise the internal energy of the fluid by 10.28 Btu. 1) Calculate the net increase in the internal energy of this system, and 2) explain how you could calculate the change in temperature of the system.

A power plant operates in an idealized Rankine cycle, using water as the working fluid (Figure 3). The steam at the exit of the boiler has a pressure of 6 MPa and temperature of 600 °C (point 1). The water at the exit of the condenser has a pressure of 15 kPa (point 3). The condenser employs a nearby river as the cooling source, which can be regarded to have a constant temperature of 25 °C. The mass flow rate of the steam is 80 kg/s. The hot reservoir has a temperature of 1400 K. Regard water as an incompressible liquid. During pumping, the density of water remains unchanged as Point 3 in Figure 3. Qin Boiler i wwwwww Pump Turbine Wp 3 Figure 3 W₁ Cooling water Condenser