Question

Consider a bathtub holding a system of water (where the boundaries of the tub are the boundaries of the system) under the following conditions:

(a) The bathtub has a closed drain and is already full of water at the start of analysis. No steam rises from the water. You want to examine heat transfer loss from the water contained in the tub over time.
(b) The bath tub drain is partially open and hot water is continually added to keep the tub filled and the temperature constant. You want to examine the flow rates required to maintain the temperature of the water in the tub.
For each system (a) and (b), determine if it is characterized as open or closed and state your reasoning.

Answer 1

a) the system is closed

b) the system is open

Step-by-step explanation:

a) the system can be characterised as closed system. If we define the boundaries of this system as an envelope that contains the bathtub, then there will not be any mass transfer to the environment through the boundary → then the system is closed ( the mass of the system remains constant)

b) on the other hand , taking the same system as in the first case, if the hot water is continually added to the tub , then there is water flow through the boundary (from the environment to the system) → then the system is open ( the mass of the system can be altered)