A large amount of water (1011 kg) is constrained to be in a water pond at a height of 500 m above sea level. At some location, a valve connects the pond to the sea through a long duct and a water turbine.
(a) How would you define a system to study the hydropower capabilities of this water?
(b) All the water in the pond and the valve is closed. What is the type of state of the system you defined in part (a)?
(c) The valve is open and water is rushing down the duct, through the turbine, and into the sea. What is the type of state under these conditions?
(d) The pond is empty and all the water has reached the sea. What is the type of state now?
