Which unit is used for velocity of flow in the example calculation?

• A. Meters per second
• B. Gallons per minute
• C. Pounds per square inch
• D. Feet per second

Answer: (D)

Velocity of flow is how far water travels in a given amount of time, so it’s a length-per-time quantity. In the example, feet are used as the length unit and seconds as the time unit, so the velocity is expressed in feet per second. Gallons per minute describes how much water flows per minute (volume per time), not how fast it moves. Pounds per square inch is a pressure unit (force per area), not velocity. If metric units were used, meters per second would be the equivalent unit.