___ pumps work on the basis of inertia or mass moving in a circular motion.

• A. Positive displacement
• B. Centrifugal
• C. Reciprocating
• D. Diaphragm

Answer: (B)

Pumps that rely on inertia of a mass moving in circular motion are centrifugal pumps. A spinning impeller accelerates the fluid outward; the liquid’s inertia tends to keep moving in the tangential direction as it is flung to the outer part of the impeller. This outward motion creates a high velocity that the pump then converts into pressure as the flow enters the volute or diffuser, delivering flow with increased head. This behavior is distinct from other pump types, which rely on trapping a fixed volume per cycle (positive displacement) or moving a piston or membrane to displace fluid (reciprocating or diaphragm pumps).