A closed system in a container, undergoes a process that takes it from state 1 to state 2. The container is rigid and so the volume of the system (water) is unchanged in the process. The only work interaction between the system and the surroundings is via the paddle wheel. The work done on the system via the paddle wheel is 220 ft*Ibf and the heat interaction can be assumed negligible.
a) Determine the increase in internal energy (in Btu) of the system.
b) What is the heat interaction needed to return the system to its original state?