Final answer:
The depth that will provide the maximum cross-sectional area and allow the most water to flow is when the pipe has a large radius and feeds into a smaller pipe.
Step-by-step explanation:
The depth that will provide the maximum cross-sectional area and allow the most water to flow is when the pipe has a large radius and feeds into a smaller pipe.
According to the principle of conservation of mass, the mass of water that enters a cross-sectional area must equal the amount that leaves.