Final answer:
The motor should stop running when the reservoir air pressure reaches 344 lbs/in². This pressure corresponds to 23.7 atm and is considered very high, potentially leading to unsafe conditions.
Step-by-step explanation:
The question pertains to the operation of a pneumatic system where the motor should stop running when the reservoir air pressure reaches a certain level, which is expressed in pounds per square inch (lbs/in²).
The provided answer choices suggest a specific pressure level for the shutdown threshold. Based on the information given, the correct answer for this system would be 61(a) which states that the motor should stop running when the reservoir air pressure reaches 344 lbs/in² or 23.7 atmospheres (atm).
This level is considered to be quite high for typical applications, as highlighted by option 61(b), indicating that this pressure might be too high for safe or practical use depending on the context, such as in a garden hose as mentioned in 61(c).
Moreover, 61(d) introduces concerns about flow rate and flow type (laminar versus turbulent), which are important factors in fluid dynamics and engineering applications.