The volume of water that passes a point during a specific time interval is?

• A. Total flow
• B. Flow rate
• C. Velocity
• D. Head

Answer: (A)

The key idea here is the difference between a rate and a quantity over time. The volume that passes a point during a specific time interval is the total amount of water that has moved in that window, i.e., the total flow. Flow rate is the amount that passes per unit time (for example, gallons per minute), and you get the total flow by multiplying that rate by the time interval. For instance, 50 gallons per minute for 10 minutes yields a total flow of 500 gallons. Velocity is how fast the water moves at a point, and head is the fluid’s energy or pressure height, neither of which describe the total volume over a period.