Answer:
The water would have a change in the energy of 50 BTU
Explanation:
- Under the assumption that the piston-cylinder system is a closed system, then the conservation law of the system would be:
, where
is all the energy that goes into the system,
is all the energy that leaves the system and,
is the change of the energy of the system.
- For this case the energy that is feeded to the system is heat: 63 BTU.
- There is two ways that energy is leaving this system: 8 BTU of heat as losses through the side walls and, 5 BTU of work done by the vapor on the piston.
- Then the change of energy of the system is:
.