Final answer:
The flow rate of a drainage system can be calculated using the formula Q = Av, where A is the cross-sectional area and v is the average velocity.
Step-by-step explanation:
Flow rate Q is defined as the volume of fluid passing through an area in a given time. It can be calculated using the formula Q = Av, where A is the cross-sectional area and v is the average velocity. In the context of a drainage system, the flow rate represents the amount of water being drained per unit of time. To determine the flow rate, you need to know the area of the drainage pipe and the velocity at which the water is being drained.